Pre-coalition arming and training of the Syrian opposition

At the direction of U.S. President Barack Obama, the Central Intelligence Agency (CIA) was put in charge of operations worth about $1 billion annually to arm anti-government forces in Syria,^{[169][170][171][172]} an operation which formally began in 2013, more than two years after the start of the civil war in 2011. Prior to 2013, the CIA only supplied certain rebel groups of the Free Syrian Army with non-lethal aid, but later began providing training, funding, and intelligence to selected rebel commanders.^{[173][174][175]} Although a former intelligence adviser who spoke to journalist Seymour Hersh claimed the CIA had been facilitating the flow of arms from Libya to Syria in collaboration with "the UK [United Kingdom], Saudi Arabia and Qatar" since 2012 or 2011,^[176] the first confirmed CIA weapons arrived in Spring 2014: "There were just a handful, delivered to only one rebel group carefully vetted by the CIA". The group, Harakat Hazm, or the Steadfast Movement, showed off the new weapons system by posting the first successful strike on YouTube in April.^[177] Another of the groups being vetted was the Islamist Army of Mujahedeen, formed in January 2014 specifically to combat ISIL.^[177][178] However, there were indications that the Army of Mujahedeen was still being vetted in September 2014.^[179]

In addition to the covert CIA program,^[180] on 17 September 2014, the U.S. House of Representatives voted to authorize the executive branch to overtly train and equip Syrian rebels against ISIL forces, at a cost of $500 million.^{[181][182][183]}

July 2014 rescue mission

Following the abduction of a number of foreigners in Syria, on 4 July 2014, the U.S. carried out an operation to rescue foreign hostages being held by ISIL. U.S. airstrikes were conducted against an ISIL military base known as the "Osama bin Laden Camp" while at the same time, two dozen U.S. special forces soldiers parachuted from helicopters near an ISIL-held building, thought to be for high-value prisoners. No prisoners were found in the building and the soldiers were quickly engaged by ISIL forces dispatched from Raqqa, which started a three-hour firefight.^[184] U.S. forces concluded that the hostages were no longer at the site and abandoned the rescue attempt. At least five ISIL fighters were killed and one U.S. soldier was wounded. Jordanian forces were also reportedly involved in the operation, with one Jordanian soldier reportedly wounded, but Jordanian involvement was not confirmed. Later on, it was reported that the hostages had been moved 24 hours before the attempted rescue.^[184] Following the mission, it remained unclear whether the operation failed due to bad intelligence or whether ISIL forces were alerted in advance of the mission.^[185]

In the aftermath of the rescue mission, and purportedly as a response to airstrikes in Iraq, ISIL beheaded three hostages over a one-month period: Americans James Foley^[184] and Steven Sotloff on 19 August and 2 September respectively, and Briton David Haines on 13 September.^[186]

Surveillance flights over Syria

On 26 August 2014, the U.S. began conducting overt surveillance flights, including drones, over Syria to gather intelligence on ISIL targets. The flights began gathering intelligence that would aid future airstrikes even though airstrikes were not yet authorized at that point.^[187] No approval was sought from the Assad government for flights entering Syrian airspace.^[188]

Support for Kurdish-led ground forces

As the Siege of Kobanî continued there were growing calls to also arm the YPG, also known as the People's Protection Units, a Kurdish fighting force in Syria heavily involved in the defense of Kobanî.^[194] On 20 October 2014, the Turkish foreign minister, Mevlüt Çavuşoğlu announced that the Turkish government would be allowing Peshmerga from the Iraqi Kurdistan Regional Government to cross their border into Kobanî to support Kurdish fighters.^[195] The change in policy came after the Turkish government had refused to allow Kurdish fighters and supplies to pass through the border to YPG units in Kobanî, as it viewed the YPG as an offshoot of the PKK.^[196] On 28 October, Peshmerga from the Iraqi Kurdistan Regional Government departed Erbil to travel to Turkey and eventually to Kobanî.^[197] A total of 152 soldiers were deployed starting with forty vehicles carrying weapons, artillery, and machine guns, along with 80 Peshmerga forces, who crossed the border into Turkey by land with the heavy weapons and then drove to the border near Kobanî.^[197] The other 72 soldiers in the contingent flew to Turkey and rejoined the rest of the contingent on 29 October.^[197] By the start of November, 152 Kurdish Peshmerga from Iraq and 50 Free Syrian Army fighters had crossed the border into Kobanî with heavy weapons, small arms, and ammunition.^[29][86]

On 20 October 2014, the United States began airdropping supplies to Syrian Kurdish forces, including the YPG, that were besieging ISIL-controlled Kobanî.^[198] Prior to 20 October, the United States and its anti-ISIL coalition partners in Syria had not provided any supplies to Kurdish forces in their fight against the jihadist group.^[198] Much of the reason for the U.S. airdropping supplies was due to the Turkish government's refusal to allow supplies to pass through their border into Kobanî. The U.S. specifically airdropped weapons, ammunition, and medical supplies supplied by Iraqi Kurdistan intended to supply the Kurdish forces in Syria.^[198] On 21 October, a video was released by ISIL showing what it claimed was a bundle of airdropped small arms, ammunition, and other supplies from the United States. The Pentagon said it was analyzing the video and could not at the time confirm whether the video was authentic but that the materials were similar; the video would subsequently be analyzed by the Department of Defense to verify its authenticity.^[199] On 22 October, the Pentagon confirmed that one of its airdrops had been intercepted by ISIL elements but downplayed the incident, saying that it most likely would not give ISIL any real advantage in their overall operations.^[200]

Coalition arming and training of the Syrian opposition

In October 2014, the Turkish government agreed to help train and equip some moderate Syrian rebels in Turkey.^[201] By January 2015, the United States was set to send 400 troops and hundreds of support staff to countries neighboring Syria in order to train 5,000 opposition soldiers a year for the next three years.^[202] The countries taking part in the train-and-equip program were to include Jordan, Qatar and Saudi Arabia, as well as Turkey.^[203] The groups that were expected to be armed and trained by the U.S. government included fighters from the Free Syrian Army.^[204] The Pentagon confirmed that it had selected 1,200 Syrian opposition members to begin training in March 2015, with 3,000 to complete training by the end of 2015.^[203]

The successful experience in Kobanî had informed U.S. policy in regard to arming Syrian opposition groups other than the Kurdish YPG, with plans to give other groups technicals equipped with radio and GPS equipment to call in airstrikes.^[180] John R. Allen, President Obama's envoy to the international coalition against ISIL, stated "It is clearly part of our plan, that not only we will train them, and we will equip them with the latest weapons systems, but we will also protect them when the time comes".^[205] In March 2015, the United Kingdom announced that it was sending around 75 military instructors to train Syrian opposition forces.^[206][207] The train-and-equip program started on 9 May 2015.^[208] On 25 May, Turkey and the U.S. agreed "in principle" on the necessity to support these forces with air support.^[209]

However, only about 200 rebel fighters actually began training, the majority of whom left after being required to agree to fight only against ISIL and not the Assad government.^[210] By mid-2015, only a group of 54 such fighters (Division 30) had been deployed – which was quickly routed in an ambush by al-Nusra^[211] – and a further 100 had been thus far finished training in Jordan.^[212] In September 2015, it was reported that a further 100-120 were being trained in a second wave,^[213] with 75 more Division 30 fighters reported to have re-entered Syria at the end of the month; they were immediately attacked by al-Nusra.^[214]

Jane's Defence Weekly reported that in December 2015 the U.S. shipped 994 tonnes of weapons and ammunition (including packaging and container weight), generally of Soviet-type equipment from Eastern Europe, to Syrian rebel groups under the ongoing CIA Timber Sycamore operation. A detailed list of weapon types and shipment weights had been obtained from the U.S. government's Federal Business Opportunities website.^[215][216] As of July 2016, extensive arms shipments were continuing.^{[217][218][219]}

It was reported in July 2017 that the Donald Trump administration decided to "phase-out" the CIA program to equip and train anti-government rebel groups.^{[220][221][222]}

Contributing countries

•  Australia (Operation Okra)
•  Bahrain
•  Belgium
•  Canada (Operation Impact § In Syria) – Airstrikes ended February 2016^[223][224]
•  France (Opération Chammal)
•  Germany (Operation Counter Daesh) – Operations in Syria ended January 2022^[225]
•  Netherlands (Dutch military intervention against ISIL and Dutch involvement in the Syrian Civil War) – Airstrikes in Syria began January 2016; anti-ISIL operations ended January 2019
•  Jordan (Jordanian intervention in the Syrian Civil War)
•  Qatar (Qatari involvement in the Syrian Civil War)
•  Saudi Arabia (Saudi Arabian involvement in the Syrian Civil War)
•  Turkey (Turkish involvement in the Syrian Civil War and Turkey–Islamic State conflict)
•  United Arab Emirates
•  United Kingdom (Operation Shader § Intervention in Syria)
•  United States (Leader) (Operation Inherent Resolve)

U.S. airstrikes

Tomahawk missiles being fired from the warships USS Philippine Sea and USS Arleigh Burke at ISIL targets in the city of Raqqa

An F/A-18 Super Hornet taking off from USS Carl Vinson before carrying out strikes on ISIL targets in Syria

In his address to the nation on 10 September 2014, U.S. President Obama announced his intention to bomb ISIL targets in Syria and called on Congress to authorize a program to train and arm rebels who were fighting ISIL and the Syrian forces of Bashar al-Assad.^[226] For the first time, he authorized direct attacks against the militant group in Syria. In his address, he said the United States were going on offensive, launching "a steady, relentless effort to take out" the group "wherever they exist." Obama also announced creating of a broader coalition against ISIL.^[227]

Commenting on Obama's address, Russian Foreign Ministry spokesman Alexander Lukashevich opposed the U.S. intervention against ISIL in Syria "without the consent of the legitimate government" and said that "this step, in the absence of a UN Security Council decision, would be an act of aggression, a gross violation of international law". Ali Haidar, Syrian minister of national reconciliation, said that "any action of any kind without the consent of the Syrian government would be an attack on Syria".^[228]

On 17 September, the U.S. House of Representatives approved Obama's plan to train and arm the Syrian rebels in their fight against ISIL. In a statement following the House vote, Obama said that the United States would not send military troops to Syria.^[229] The Senate gave final congressional approval to Obama's proposal the next day.^[230]

The U.S. did not request permission from the Syrian government, nor did it coordinate its actions with the Syrian government, provide direct notification to the Syrian military or give indication of timing on specific targets, but it did notify the Syrian U.N. representative, which the Syrian government confirmed.^[231]

Before the airstrikes began, the United States also informed Iran, the Assad government's largest regional ally, of their intention to launch airstrikes. It did not share specific timing or targets of strikes with the Iranian government but reportedly assured it that the US would not strike any Syrian government targets.^[232]

On 8 April 2018, U.S. President Donald Trump called Syrian President Bashar Al-Assad "Animal Assad", following suspected chemical attack carried out in the Syrian city of Douma.^[233] On 14 April, the United States, France, and the United Kingdom carried out missile strikes against Syria. On 30 May, President Al-Assad responded to the insult, by saying: "What you say is what you are."^[234]

It was reported in June 2018 that the 441st Air Expeditionary Squadron reportedly maintained an unpaved runway in Sarrin, Raqqa Governorate.^{[235][236][237]}

On 14 June 2020, a U.S. coalition drone strike killed Guardians of Religion Organization leaders Khalid al-Aruri and Bilal al-Sanaani who were driving a vehicle in Idlib.^[238] There was reportedly no explosion and the target vehicle was relatively intact, with the roof and windshield impacted from above and one side shredded, leading observers to suggest the munition used was probably the kinetic Hellfire R9X missile that uses blades to eviscerate its target rather than an explosive warhead.^[239] On 24 June, Abu Adnan al-Homsi, logistics and equipment commander at the Guardians of Religion Organization, was also killed by a U.S. drone strike.^[240]

On 25 February 2021, U.S. military airstrikes commanded by U.S. president Joe Biden destroyed multiple facilities related to pro-Iranian militias including Kata'ib Hezbollah and Kata'ib Sayyid al-Shuhada, at a border control point near al-Hurri village, Abu Kamal District, in retaliation to Erbil missile attacks.^[241][242] At least 17 militants were reported killed in the strikes, although the militias only confirmed one.^[243] The strikes were conducted by two F15s dropping Joint Direct Attack Munitions (JDAM) and was the first overt military operation ordered by the Biden administration.^[244]

On 28 June 2021, the U.S. military conducted airstrikes on facilities purportedly used by Iranian-supported militias near the Iraq–Syria border.^[245] However, the SOHR stated that at least nine Iran-backed Iraqi militia fighters died, and many others were injured.^[246]

Airstrikes on the Khorasan Group

F/A-18 Hornets take off from USS George H.W. Bush to strike ISIL targets in Syria, 2014

One of the groups targeted by U.S. airstrikes was the Khorasan Group, an extremist group of suspected al-Qaeda "core" members who were alleged to have been plotting an attack against the U.S. and other Western nations.^[231] The strikes targeted Khorasan training camps, explosives and munitions production facilities, communications facilities, as well as command and control facilities. The group has been claimed to possess advanced bomb making skills and their plot is claimed to involve a bomb made of a nonmetallic device such as a toothpaste container or clothes dipped in explosive material.^[247] The group is reportedly led by Muhsin al-Fadhli, a leader of al-Qaeda and a close confidant of Osama bin Laden.^[247] Intelligence officials expressed concern that the group may include militants who were taught by Ibrahim al-Asiri, the chief bomb maker for al-Qaeda in the Arabian Peninsula, who is known for his sophisticated bomb making techniques that nearly downed two Western airliners.^[247]

Later statements by government officials indicated that the threat of a plot may have been less severe than initially reported.^[248][249] One official indicated that "there did not yet seem to be a concrete plan in the works",^[248] while another told The Guardian that "there was no indication of an imminent domestic threat from the group" at the time the United States began bombing.^[249]

On 6 November, a second round of airstrikes was launched against Khorasan and al-Nusra in northwestern Syria, along with Ahrar ash-Sham at its headquarters in Idlib, whose leadership had been infiltrated by al-Qaeda.^[46] On 13 November 2014, the US launched a third set of airstrikes against Khorasan.^[250] On 19 November, the US carried out another airstrike on Khorasan near Hazm, which struck and destroyed a storage facility associated with the group.^[251] On 1 December, the US carried out another airstrike on Khorasan near Aleppo.^[252]

On 24 March 2015, it was revealed that the US airstrikes on Khorasan had killed 17 militants from the group.^[253]

On 8 July 2015, a US airstrike near the town of Sarmada in Idlib, Syria, killed Muhsin al-Fadhli, the leader of Khorasan.^[66]

2015–16

U.S.-backed Syrian Democratic Forces fighters in Manbij, 2016

In November 2015, the Obama administration began the deployment of U.S. special forces to Syria, with the mission of assisting rebel forces in their fight against ISIL, President Obama then ordered several dozen Special Operations troops into Rojava in northern Syria to assist local fighters battling ISIL, authorizing the first open-ended mission by American ground forces into the country.^[257]

ISIL's deputy leader in Syria, Abu Ali al-Anbari, was killed by JSOC special forces operatives in March 2016, in eastern Syria near the Syrian–Iraqi border, while he and three other ISIL members were traveling in a vehicle coming from Raqqa. The US Special Forces ordered him to exit the vehicle, intending to arrest him. When he refused and pulled out an assault rifle instead, US forces fired at the vehicle, killing him and the other passengers on board. US commandos also seized electronics and other documents during the operation for intelligence purposes.^[258]

In March 2016, King Abdullah of Jordan said that British forces had helped in the building up of a mechanized battalion in southern Syria, consisting of tribal fighters to combat the Syrian Army.^[259]

On 17 March 2016, the day after the declaration of the Federation of Northern Syria, U.S. Defense Secretary Ashton Carter praised the Syrian Democratic Forces as having "proven to be excellent partners of ours on the ground in fighting ISIL. We are grateful for that, and we intend to continue to do that, recognizing the complexities of their regional role."^[260]

U.S. Army Special Forces in Raqqa, May 2016; one is wearing a Kurdish YPJ patch

During the SDF's May 2016 offensive against ISIL in Northern Raqqa, U.S. Special Forces were widely reported and photographed to be present, with some of them wearing badges of the Kurdish YPG and YPJ on their uniforms.^[261] On 21 May, Joseph Votel, commanding general of U.S. Central Command, completed a secret hours-long trip to northern Syria to visit several locations where there were U.S. special operations forces and meet with local forces the U.S. was helping train to fight ISIL. The visit came as the first of 250 additional U.S. special operations forces were beginning to arrive in Syria to work with local forces. The commander overseeing the war in Syria, at the end of a long Saturday spent touring SDF bases, said "We do, absolutely, have to go with what we've got".^[262]

In September 2016, the U.S. spokesman for the Combined Joint Task Force – Operation Inherent Resolve (CJTF–OIR) confirmed that the SDF, including the YPG, is also part of the "vetted forces" in the train and equip program and would be supplied with weapons. The President of Turkey, Recep Tayyip Erdoğan, condemned this and claimed that the SDF are "endangering our future".^[263]

In October 2016, U.S. Army Lt. Gen. Stephen J. Townsend, the commander of the international coalition against ISIL, said that the SDF would lead the impending assault on Raqqa, ISIL's then-stronghold and capital, and that SDF commanders would plan the operation with advice from American and coalition troops.^[264] From November 2016, more than 300 U.S. Special Operations Forces were embedded to train and advise SDF fighters in the Raqqa offensive.^[265]

2017–18

Kurdish troops and U.S. armored vehicle in Al-Hasakah, May 2017

U.S. Army 310th Engineer Company maintaining a Mabey Logistic Support Bridge during the Battle of Raqqa, 29 July 2017

In March 2017, the Trump administration deployed an additional 400 U.S. Marines to Syria to expand the fight against ISIL in the Raqqa offensive where they could provide artillery support for U.S.-backed local forces that were preparing an assault on Raqqa to liberate the city from IS militants. The deployment marked a new escalation in the U.S.'s war in Syria, and put more conventional U.S. troops in the battle that, until then, had primarily used Special Operations units. The 400 Marines were part of the 11th MEU from the Battalion Landing Team 1st Battalion, 4th Marines. They manned an artillery battery of M-777 Howitzers whilst additional infantrymen from the unit provided security; resupplies were handled by part of the expeditionary force's combat logistics element.^[266] During the Raqqa campaign alone, this small artillery battalion fired over 40,000 shells (including 34,033 155 mm), more than were used in the entire 2003 invasion of Iraq and only 20,000 fewer than all those fired by the U.S. military in Operation Desert Storm.^[267]

In March 2018, SDF press secretary in Deir ez-Zor Mehdi Kobani reportedly told Sputnik Turkiye that U.S. forces were building a "large military base" in the oil-rich al-Omar region of Deir ez-Zor as new equipment had been reportedly arriving to U.S. bases in Syria. The al-Omar oilfield is the largest oil deposit in Syria, and was captured by the SDF during their campaign against ISIL in October 2017.^[268][269]

2019 drawdown of U.S. ground forces

On 19 December 2018, President Donald Trump announced that he ordered the pullout of all 2,000–2,500 U.S. troops operating in Syria, though no clear timetable was given.^[270] A day later, after failing to convince Trump to reconsider his decision to withdraw all American troops from Syria, Jim Mattis announced his resignation as Secretary of Defense.^[271] On 3 January 2019, Trump described Syria as "sand and death" in defense of troop withdrawal.^[272] U.S. operations in al-Tanf would continue indefinitely.^[273]

On 16 January 2019, a suicide bombing claimed by ISIL in the SDF-controlled town of Manbij killed four U.S. personnel and injured three servicemen, making it the deadliest attack on Coalition forces in the country since the intervention.^{[274][275][276]} The ISIL attack drew a second round of criticism of the U.S. president's withdrawal order, with critics linking the attack with an emboldening of ISIL terror and insurgent tactics due to the announcement of a U.S. pullout, despite the group's continued loss of territory in Syria.^[277] President Trump offered condolences to the families of the slain American citizens on 17 January while he reaffirmed his policy of withdrawing troops.^[278] Trump paid tribute to the fallen Americans during a trip to Dover Air Force Base in the U.S. state of Delaware on 19 January, where their remains were received.^[279]

On 21 January, an ISIL SVBIED targeted a U.S. convoy accompanied by SDF troops on the Shadadi-Al-Hasakah road in Al-Hasakah province, killing five SDF personnel. Witnesses said the SVBIED rammed into an SDF vehicle by a checkpoint held by Kurdish forces a dozen kilometers outside Shadadi as the U.S. convoy drove past. No Americans were harmed.^[280]

CNN reported on 24 January that additional U.S. troops were moved to Syria to help provide security for the pullout of equipment and personnel as they are moved out via air and land routes. U.S. Department of Defense officials said the additional security forces would move around Syria to different locations as needed and may move in and out of the country at times. Troop numbers would also fluctuate as American presence gradually declines. Defense officials declined to give specifics on numbers, locations, or timetables, citing security concerns.^[281] Local sources reported to Anadolu Agency on 28 January that around 600 U.S. troops had allegedly entered eastern Syria from western Iraq to help with the withdrawal process, arriving at discreet bases in Harab Isk and Sarrin villages set to be used as main evacuation centers during the withdrawal. The news agency added that the American-controlled airfields in Rmeilan and Tell Beydar would be used to airlift heavy weapons and equipment from the country; the Coalition itself did not confirm these reports.^[282]

By the end of January 2019, according to two U.S. officials, more than 10 percent of American equipment and supplies had been removed from Syria, with 3,000 additional personnel brought into the country to facilitate the draw-down of forces. By 9 February, hundreds of U.S. airstrikes and ground support for the SDF continued as the Kurdish-led force began its final assault on the last ISIL holdouts trapped in a small cluster of hamlets in eastern Syria (including Al-Baghuz Fawqani and southern Al-Marashidah) no larger than a few square miles. U.S. officials, including President Donald Trump, believed the SDF would be able to defeat the remaining diehard ISIL fighters "in days", bringing an end to ISIL's claim of a territorial caliphate.^[283]

On 18 February, Commander-in-Chief of the SDF Mazlum Kobane expressed hopes the U.S. would halt its total pullout. Kobane said there were discussions about perhaps French and British troops supporting them, but demanded 1,000–1,500 U.S. troops stay in Syria to provide "air cover, air support and a force on the ground" to help the SDF in its ongoing fight against ISIL. CENTCOM commander Gen. Joseph Votel reiterated the U.S. withdrawal was continuing.^[284]

With the general withdrawal continuing, the White House announced late on 21 February that 200 residual U.S. troops would remain in Syria as a "peacekeeping force". The peacekeeping deployment would be indefinite.^[285] The next day it was revealed the actual number was 400 troops, not 200, as half would be based in Rojava and half at al-Tanf. Officials stated it was a part of an initiative to get NATO allies to commit to a multinational observer force that would establish a "safe zone" in Rojava to keep the Kurds and Turks from clashing, to prevent pro-Syrian government forces from attacking the Kurds, and to keep up pressure to prevent an ISIL resurgence. The U.S. was not seeking a United Nations mandate for the deployment and did not envision asking NATO to sponsor the mission, an administration official said at the time, adding that the troops would not technically be "peacekeepers," a term that carries restricted rules of engagement.^[286]

On 7 March, Gen. Joseph Votel confirmed that U.S. forces were in no rush to pullout by a specific date, instead saying the completion of the withdrawal was conditional on ISIL no longer posing a security threat to U.S. forces and their allies.^[287] By late March, the U.S. continued to stretch the timetable for the pullout. On 29 March, U.S. officials reportedly said the Pentagon's latest plans called for cutting its combat force in northeastern Syria roughly in half by early May 2019, or to about 1,000 troops, and would then pause pullout operations. The military would then reduce the number of forces every six months, depending on conditions on the ground, until it reaches the 400 troops previously approved by the president. Under this plan, the lowest troop numbers would not be reached until autumn 2020. The longer timetable would provide the U.S. more time to negotiate and work out details over the planned multinational safe zone along Turkey's border. Officials cautioned that the timetable was open-ended and still subject to change, with factors ranging from allied troop contributions to new orders from the president himself.^[288]

In early May, video emerged online of U.S. forces firing upon an alleged Syrian government barge ferrying oil supplies in the Middle Euphrates River Valley. The video was posted on Facebook by the pro-SDF "Deir Ezzor Media Center".^[289]

2019–20: Eastern Syria redeployment

4th Battalion, 118th Infantry Regiment (attached to 218th MEB) at a staging area in Syria, 10 November 2019

By 20 October 2019,^[299] after backlash from the U.S. Congress, the Trump administration had conducted a partial reversal of its 6 October order to pullout 1,000 troops from Syria, instead confirming a newly dedicated mission to guard oil and gas fields and related infrastructure in SDF-controlled eastern Syria from ISIL insurgent attacks. While U.S. forces continued to reduce its presence in northern Syria by the hundreds to avoid Syrian-SDF and Turkish fighting, the U.S. simultaneously shifted more resources south and east into the oil-rich Deir ez-Zor Governorate.^[299] Defense Secretary Mark Esper confirmed on 25 October that the U.S. would "maintain a reduced presence in Syria and deny ISIS access to oil revenue"^[299] and, in support of the mission, mechanized and armored units would be deployed to eastern Syria to reinforce the American presence there.^[298] Throughout late October-early November 2019, this contingent was reinforced with hundreds of new infantry troops joined by mechanized infantry Armored Brigade Combat Teams (ABCTs) in Bradley IFVs and—according to unnamed sources—potentially tanks, redeployed from Iraq and Kuwait, which was estimated to raise the number of U.S. troops in eastern Syria to around 500 at the time. When coupled with the U.S. garrison at al-Tanf, the contingency force's numbers rise to a flexible 800–900 personnel.^[299] In Syria's Deir ez-Zor Governorate, which lies far to the North-East of al-Tanf, the United States has stated that it will increase its presence in SDF controlled territory along the Eastern bank of the Euphrates river and also establish military bases at al-Baghuz, al-Basira, al-Ezba, and the al-Omar oil field.^[307]

M2A2 Bradley IFVs of the 4th Battalion, 118th Infantry Regiment accompany a patrol in eastern Syria, 13 November 2019

On 30 October, 4th Battalion, 118th Infantry Regiment, a U.S. combined arms battalion equipped with M2A2 Bradley IFVs deployed to the Deir ez-Zor region to help guard SDF-U.S. controlled oil and gas fields. The battalion is part of the U.S. Army National Guard's 30th ABCT which had begun arriving in Kuwait the week prior to relieve the regular Army 3rd Brigade Combat Team, 4th Infantry Division in support of Operation Spartan Shield, the U.S.'s theater-level contingency force for the Middle East.^[308] By 31 October, U.S. forces in M-ATV convoys were seen conducting dedicated patrols of oil and gas-related facilities throughout Syria's al-Hasakah and Deir ez-Zor Governorates, usually accompanied by SDF personnel. The U.S.'s deployment of heavy armored vehicles to Syria for the first time in the intervention—as opposed to the lighter armored RG-33s, M-ATVs, Strykers, Armored Ground Mobility Systems, and NSTVs (Non-Standard Tactical Vehicles) U.S. special operations units and regular ground forces have used prior—introduced additional firepower and force protection capabilities for ground forces.^[308] Nevertheless, the Bradley IFVs were pulled out of Syria after less than two months of deployment due to unspecified reasons.^[309]

On 3 November, OIR officials confirmed that multiple artillery rounds landed about one kilometer from a road with a U.S. convoy; OIR, without offering additional details, stated no personnel were injured and the patrol was not hit. The Russian Defense Ministry were the first to report the incident, adding that the incident was near Tell Tamer and that it was elements of Turkish-backed rebels that fired the artillery.^[310] On 4 November, Rudaw briefly interviewed a U.S. special operations soldier during a patrol at an oilfield near Rmelan, who stated that U.S. forces are "working with the SDF and they're letting us know the situation up here as they see it." According to North Press Agency, the U.S. patrol had begun in Rmelan and spanned the towns of al-Jawadiyah, al-Malikiyah, and Ain-Diwar.^[311] On 15 December, a large U.S. logistical convoy en route to Deir ez-Zor was reportedly seen crossing Semalka into al-Hasakah province from Iraq.^[312]

By mid-January 2020, tensions between Russian and U.S. forces in northeast Syria had reportedly grown as U.S. troops had increasingly begun blocking Russian convoys from accessing certain major roads between towns. Both Russia and the U.S. operate military outposts throughout the region as a part of their respective missions.^[313] On 25 August, a Russian military vehicle rammed a U.S. armored car near al-Malikiyah, northeastern Syria, in which four US soldiers had suffered mild concussions. Russian defense minister Sergey Shoygu said that "the US armed forces soldiers tried to block the Russian patrol"; meanwhile, a US defense official said that Russian forces went to a "security zone" that they should not enter.^[314]

On 30 July 2020, the Autonomous Administration of North and East Syria signed an agreement with an American oil company, Delta Crescent Energy LLC, to develop oil fields in the region.^[315] The Syrian authorities condemned the agreement, and mentioned that: "This agreement is null and void and has no legal basis."^[316] Seizing oil without local government permission would be a war crime of pillage.^[317]

On 17 August, U.S. forces killed at least one Syrian soldier and wounded two others, after a fire exchange near a checkpoint in the village of Tal Dahab, near Qamishli, northeastern Syria.^[318]

On 19 September, the U.S. deployed additional troops, equipment and armored vehicles to north-eastern Syria after tensions with Russia escalated in the region. According to officials, the moves were meant "to help ensure the safety and security of coalition forces."^[319] U.S. Central Command mentioned that the United States had deployed Sentinel radars and Bradley vehicles to augment forces in the "Eastern Syria Security Area" (ESSA).^[320] The reinforcements were considered a response to a 26 August incident where a Russian armored vehicle collided with a coalition M-ATV, injuring four U.S. soldiers.^[321]

2021–present: Continued Iranian—U.S. proxy conflict

U.S. 1st Battalion, 6th Infantry Regiment troops conduct area reconnaissance in Syria, 18 February 2021

On 10 February 2021, Pentagon Press Secretary John Kirby told reporters that U.S. troops were not committed to protecting Syrian oil fields except "for where appropriate under certain existing authorizations to protect civilians." He added that "DOD [Department of Defense] personnel or contractors are not authorized to provide assistance to any other private company, including its employees or agents, seeking to develop oil resources in northeastern Syria."^[9] However, there were reports from local sources in northeastern Syria that U.S. forces had transported oil and wheat smuggled from Syria to Iraq.^[322]

On 20 October 2021, troops at the al-Tanf garrison were attacked by bomb-laden drones in what Pentagon spokesman John Kirby called a "complex, coordinated and deliberate attack". U.S. officials reportedly blamed Iran and its proxy forces for the attack, but publicly declined to specify details of the attack and whether the U.S. was considering retaliation. There were no reports of deaths or injuries. Attacks by small drones carrying munitions have posed a consistent threat to U.S. forces in eastern Syria since at least March 2020, with U.S. forces suspecting ISIL or Iran-backed elements of conducting the attacks, as U.S.-Iranian tensions in the region have persisted.^[323]

Northern Syria Buffer Zone

U.S. and Turkish soldiers rendezvous in the Northern Syria Buffer Zone, 4 October 2019.

On 15 January 2019, the Turkish President Recep Tayyip Erdogan said he agreed with setting up a 35 km (22 mi) "safe zone" in northern Syria, after engaging with U.S. President Donald Trump a few days prior.^[341]

On 7 August 2019, after months of negotiations, Turkey and the U.S. reached a deal to create a 115 km (71 mi) buffer zone in northern Syria along the Syria–Turkey border between the Tigris and Euphrates rivers. Separate from Turkey's own occupation zone in northern Syria, the deal was reached partly to prevent a potential future Turkish ground incursion into Rojava against U.S.-backed Kurdish forces. Under the framework of the deal, the U.S. and Turkey conducted joint troop patrols, and Turkish reconnaissance aircraft would be allowed to monitor the zone. Kurdish YPG and YPJ forces along the Turkish border dismantled their border fortifications, withdrew to a "security belt" alongside regular SDF forces, and removed all heavy weapons from the area. In turn, Turkey was not to conduct airstrikes or establish military observation posts in northern Syria, and was not to "occupy" the region, as administrative and civil rule was to be relegated to SDF military councils and the Kurdish Autonomous Administration of North and East Syria. According to the SDF, the majority of the zone was not to include any cities or towns.^[342]

The buffer zone agreement was proven to be short-lived and collapsed on 7 October, after U.S. President Donald Trump gave his approval for a Turkish ground offensive into Rojava, and ordered the withdrawal of U.S. troops from northern Syria. The agreement was rendered fully obsolete on 9 October, when Turkey launched a ground incursion into Rojava.^[343] In response to the offensive, U.S. Senator Lindsey Graham warned that he would “introduce bipartisan sanctions against Turkey if they invade Syria.” He said he would also "call for their suspension from NATO if they attack Kurdish forces who assisted the U.S. in the destruction of the ISIS Caliphate."^[344]

Domestic U.S. approval

The intervention was initially conducted with strong domestic U.S. support; according to Gallup polling in 2014, 61% of Americans supported intervention against ISIL in both Iraq and Syria, while 30% were opposed, and 9% undecided.^[375] A larger CCGA poll taken in 2016 showed that 72% of Americans supported "conducting airstrikes against violent Islamic extremist groups in Syria", while 58% also supported "sending special operations forces into Syria to fight violent Islamic extremist groups." Additionally, a slim majority (52%) supported "enforcing a no-fly zone over parts of Syria, including bombing Syrian air defenses." However, only 26% supported "sending arms and other supplies to anti-government rebel groups in Syria."^[376]

A CNN poll conducted between 17 and 20 October 2019—during a withdrawal of U.S. troops from northern Syria amid a Turkish offensive there—showed that 75% of Americans were generally concerned about the situation in Syria, with 43% saying they were "very concerned". 51% thought the U.S. had a responsibility to remain involved in the Syrian conflict (seven months after ISIL's final Syrian settlement had fallen), while 43% did not.^[377]

Syrian reactions

•  Syria – In 2014, a week before the first airstrikes, Ali Haidar, the Syrian Minister of National Reconciliation, said that "any action of any kind without the consent of the Syrian government would be an attack on Syria".^[228] However, despite Haidar's original statement, after the coalition campaign began, the Syrian government struck a more conciliatory tone with Foreign Minister Walid al-Moallem suggesting the airstrikes were an indication that Syria and the anti-ISIL coalition were on the same side.^[378] Among the general Syrian population, a July 2015 poll by ORB International surveying 1,365 adults in all of Syria's 14 governorates found that 47% supported U.S.-led airstrikes on ISIL while 50% opposed them.^[379] Opposition to American airstrikes was strongest in ISIL-held territory, where 92% were opposed; support was strongest in YPG-held territory and government-held territory, where 87% and 55% respectively supported American strikes on ISIL.^[380]
• Syrian opposition – Hadi Bahra, the leader of the National Coalition for Syrian Revolutionary and Opposition Forces called for airstrikes against ISIL before the intervention began. The coalition is recognized by 20 countries, the European Union, and the Arab league as the legitimate representative of Syria in opposition to the Assad government. Bahra said strikes were needed to weaken ISIL, a faction in the inter-rebel conflict during the Syrian Civil War, so that the Free Syrian Army and other moderate opposition forces could oppose Assad more effectively.^[381] Despite Bahra's support, many Syrian rebel groups have criticized U.S. airstrikes for targeting only ISIL who are enemies of the Assad government, while not also targeting Assad government forces, the results of which could help government forces gain more ground.^[348] Meanwhile, jihadist groups within the opposition have portrayed the coalition as an anti-Sunni stooge of the Syrian regime,^[382] while many Sunnis in Syria are angered that only extremist Sunnis are being targeted while mostly Shiite Assad forces are not targeted.^[383] Some rebels defected to extremist groups as a result of the U.S. decision to strike jihadist groups other than ISIL, such as the al-Nusra Front.^[384]

International reactions

In a Pew poll taken in 2015, a median of 62% of people across the nations polled said they support American military efforts against the Islamic State group in Iraq and Syria, while a median of 24% were opposed. Among those in support were 78% of Lebanese, 77% of Jordanians, 48% of Turks, 53% of Palestinians, and 84% of Israelis, as well as 81% of French, 66% of British, and 62% of Germans.^[385]

•  Australia – Tony Abbott, the Prime Minister of Australia, praised the intervention, saying that an international effort was needed in order to combat the ISIL threat.^[231] Despite Abbott's support for the intervention, the Australian Government said it is not likely to contribute forces to operations in Syria.^[386]
•  Canada – Stephen Harper, the Prime Minister of Canada, said in October 2014 Canada would strike ISIL targets in Syria if the Assad government gave approval.^[387] New Prime Minister Justin Trudeau called President Obama almost immediately after coming into office to inform him that Canada will be ceasing air operations in coordination with Americans. Trudeau did not give a time frame.^[388]
•  Czech Republic – Lubomír Zaorálek, the Minister of Foreign Affairs of the Czech Republic supported the intervention against the Islamic State and said that it is important to keep supporting the ground forces in the battle against ISIS and the Czech Republic will keep providing military support to the Iraqi army and to the Kurdish Peshmerga. He also noted that air strikes would not defeat Islamic State. The Czech government said that ISIS is enemy not only for safety in the Middle East, but also for security and stability in the Czech Republic and Europe.^[389]
•  Ecuador – The Ecuadorian government opposed the airstrikes in Syria without the consent of the Syrian government.^[390]
•  Egypt – Egyptian President Abdel Fattah el-Sisi expressed his government's support for the international campaign against ISIL, and a spokesperson for the Egyptian foreign ministry echoed his statements by reiterating the Egyptian government's willingness to back the war against ISIL.^[391][392]
•  Germany – German foreign minister Frank-Walter Steinmeier questioned whether President Obama's plan was adequate in order to combat ISIL and said Germany had not been asked to participate in airstrikes nor would it participate if asked.^[393]
•  Iran – Iranian President Hassan Rouhani condemned ISIL's actions but also called the airstrikes in Syria "illegal" because they were conducted without the consent of the Syrian government.^[394] Iran's deputy foreign minister Hossein Amir Abdollahian was reported in Iranian media as saying that Iran had warned the United States that Israel would be at risk should the US and its allies seek to topple Syrian president Bashar al-Assad while fighting ISIL in Syria.^[395]
•  Israel – Israeli Prime Minister Benjamin Netanyahu said Israel fully supported the U.S. government's calls for united action against ISIL.^[393]
•  Japan – A spokesperson for the Japanese Ministry of Foreign Affairs said the Japanese government would continue to closely coordinate with the United States and other countries, along with offering support and cooperation in their strikes against ISIL.^[396]
•  Netherlands – Mark Rutte, the Prime Minister of the Netherlands, showed understanding for the intervention against ISIL in Syria and said that his government was exploring options to contribute in the fight against ISIL.^[397]
•  Russia – Alexander Lukashevich, Russian Foreign Ministry spokesman, opposed the military intervention "without the consent of the legitimate government" and said that "this step, in the absence of a UN Security Council decision, would be an act of aggression, a gross violation of international law".^[228] On 14 October, Russian Foreign Minister Sergey Lavrov questioned the motives of the intervention, saying "Maybe their stated goal is not entirely sincere? Maybe it is regime change?" He also questioned the effectiveness of the year long campaign "With, as far as I know, 25,000 sorties they [US-led air campaign] could have smashed the entire [country of] Syria into smithereens," continuing to remark that "positive results 'on the ground' are not visible". He also criticized the continued supply of arms to rebels, saying "I want to be honest, we barely have any doubt that at least a considerable part of these weapons will fall into the terrorists' hands." He continued to call for the countries involved to join a coalition made up of Russian, Syrian, Iranian, Iraqi, Jordanian and Hezbollah forces against what Russia claims is solely ISIL and al Qaeda, but the US has asserted is primarily non-jihadist opposition forces.^[398]

Dmitry Peskov, spokesman for the Russian President Vladimir Putin, described the US air strikes on the Shayrat airbase as "an act of aggression against a sovereign state delivered in violation of international law under a far-fetched pretext.... a serious blow to Russian-US relations, which are already in a poor state".^[399]

Foreign Minister Sergei Lavrov referred to the Sharyat attack as "an act of aggression under a completely invented pretext". He compared events in April 2017 to "the situation of 2003, when the USA, the UK and several of their allies invaded Iraq without the UN Security Council's approval – a grave violation of international law – but at that point they at least tried to show some material evidence."^[399]

•  Turkey – The Davutoglu Government called on the Grand National Assembly of Turkey to approve measures that would grant extensive authority to the President to launch military operations in both Syria and Iraq, including the authority to send troops across the border, although it is unclear whether the Turkish leadership intends to act on that authority. President Recep Tayyip Erdoğan has urged the establishment of a no-fly zone by coalition forces in northern Syria.^[400]
•  United Kingdom – A spokesperson for British Prime Minister David Cameron said the UK would not rule out airstrikes in Syria against ISIL.^[393] On 26 September 2014 Parliament voted 524 to 43 to approve action inside Iraq.^[401] While visiting Iraqi Kurdistan in mid October, British Foreign Secretary Philip Hammond said he saw no immediate demand from U.S. and Arab militaries for Britain to extend its airstrikes to Syria.^[402] British Defense Minister Michael Fallon said on 21 October that British Reaper drones and Rivet Joint surveillance aircraft would be starting intelligence-gathering missions in Syria "very shortly."^[82]
•  United States – In November 2019, President Donald Trump ordered U.S. troops to secure the oil fields in eastern Syria, then said any remaining U.S. troops in Syria were there "only for the oil", and that the U.S. was "keeping the oil".^[317][403]
•  United Nations – Ban Ki-moon, UN secretary-general, welcomed the airstrikes against militants in Syria, but noted that the involved parties "must abide by international humanitarian law and take all precautions to avoid and minimize civilian casualties".^[404]
•  Venezuela – At the 69th General Assembly of the United Nations, President Nicolas Maduro said "It's President Bashar al-Assad and the Syrian government which have stopped the terrorists" and continued by saying "Instead of bombing and bombing, we must make an alliance for peace".^[405][406]