Battle of Khasham

On 7 February 2018, the U.S.-led coalition, established in 2014 to counter the Islamic State of Iraq and the Levant (ISIL), delivered massive air and artillery strikes on the Syrian pro-government forces near the town of Khasham, or Al Tabiyeh, both in the Deir ez-Zor Governorate. The United States explained the attack by stating that the pro-government forces had ″initiated an unprovoked attack against well-established Syrian Democratic Forces headquarters" in the area, while Coalition service members were ″co-located with SDF partners during the attack eight kilometers east of the agreed-upon Euphrates River de-confliction line″. The Russian defence ministry′s statement released on 8 February 2018 referred to the incident at the village of Salihiyah (located south of the SDF-held town of Abu Hamam in  the Abu Kamal District) and said that it was caused by reconnaissance actions of Syrian militia that had not been cleared with the Russian operations command; the statement stressed that there were no Russian service members in the ″designated district of the Deir ez-Zor province of Syria".

The U.S. military stated that one hundred Syrian pro-government fighters were killed in the U.S. attack, prompting Syria to accuse the United States of carrying out a "brutal massacre" of its troops and Russia to accuse the U.S. of being economically motivated in its actions, citing nearby oil fields. As information about casualties among Russian citizens in the strike emerged, the incident was billed by media as "the first deadly clash between citizens of Russia and the United States since the Cold War."

Background
In September 2014, the United States began to undertake efforts to establish a global coalition with the declared aim of countering ISIL in Syria, as well as in Iraq. Since 22 September 2014, the U.S. had conducted military operations in Syria, primarily against ISIL forces as part of Operation Inherent Resolve. The primary U.S-backed force in the northeastern part of Syria had been the Syrian Democratic Forces, a group composed predominantly of Kurdish and Arab militiamen. In 2017, backed by the U.S. forces, the SDF captured Raqqa from the Islamic State and has since advanced to the Euphrates River, where a "deconfliction line" was established through coordination by the governments of the U.S. and Russia. On several occasions, U.S. forces struck Syrian pro-government units operating in the area. In November 2017, the U.S. government made it known that they were expanding their goals in Syria beyond routing ISIL forces, to pressure the Syrian government to make concessions at the Geneva talks. This intent was, in mid-January 2018, clearly broadcast by Secretary of State Rex Tillerson, who said the Trump administration would maintain an open-ended military presence in Syria to counter Iranian influence and ensure the departure of Syrian President Bashar Al-Assad.

Russia had been conducting air military operations in Syria in support of the Syrian government since 30 September 2015. Furthermore, Russian private military contractors (″volunteers″), notably those associated with the Wagner Group, had been engaged in ground operations since approximately the same time, although their presence was never officially confirmed by the Russian government.

On 13 February 2018, Lt. Gen. Jeffrey L. Harrigian, Commander of U.S. Air Forces Central Command, talked about the circumstances before the attack: "The coalition observed a slow buildup of personnel and equipment the previous week, and we reminded Russian officials of the SDF and coalition presence via the telephone deconfliction line. This was well in advance of the enemy forces' attack. I know you're going to ask, so I'm going to be clear that I will not speculate on the composition of this force or whose control they were under." Harrigian presented the U.S. strike as demonstration of the coalition′s readiness ″to prevent a resurgence of ISIS".

On 22 February 2018, The Washington Post cited unnamed sources in the U.S. intelligence as alleging that the communications intercepted days before and after the incident between Russian businessman Yevgeniy Prigozhin, who was believed to finance the Wagner Group, and senior Syrian officials, such as Mansour Fadlallah Azzam, as well as Kremlin officials, suggested that Prigozhin had "secured permission" from an unspecified Russian minister to go ahead with a "fast and strong" move in early February and was awaiting approval from the Syrian government. Prigozhin was one of the persons who was in mid-February 2018 indicted by the Grand Jury for the District of Columbia on charges related to the Special Counsel investigation led by Special Counsel Robert Mueller. A publication by the Ukraine-based anti-Kremlin Inform Napalm alleged the battle was planned and cleared with the Russian military command by Sergey Kim, the chief of Wagner′s operations department and a former Russian Marine officer.

U.S. version
According to the U.S. military′s official statement, around 10 p.m. local time on the night of 7 February 2018, a force of 500 pro-government fighters consisting of local militiamen, government soldiers, Iranian-trained Afghan Shia fighters, and reportedly Russian contractors launched an assault on a Syrian Democratic Forces headquarters near the town of Khasham, located on the Euphrates River in Syria. Supported by T-72 and T-55 tanks, the pro-government troops first shelled the SDF base with artillery, mortars, and rockets in what U.S. military officials described as a "coordinated attack." Around 20–30 shells landed within 500 meters of the headquarters. According to the U.S. military, the presence of U.S. special operations personnel in the targeted base elicited a response by U.S.-led coalition aircraft, including AC-130 gunships, F-15E Strike Eagle fighter jets, unmanned aerial vehicles (MQ-9), AH-64 Apache attack helicopters, B-52s, and F-22s. Nearby U.S. Marine artillery batteries, including a High Mobility Artillery Rocket System, shelled Syrian forces as well. According to sources in the Russian private military company, Wagner Group - cited by news media as well as the Pentagon - U.S. forces were in constant contact with the official Russian liaison officer posted in Deir ez-Zor throughout the engagement and only opened fire after they had received assurances that no regular Russian troops were in action or at risk.

The clashes lasted four hours and saw more than 100 Syrian pro-government fighters killed, with just one SDF fighter wounded, according to the U.S.-led coalition. No U.S. troops were killed or wounded.

According to two U.S. defense officials, cited by CNN on 8 February, the U.S. military had assessed that Russian contractors had been involved, with one saying some of the contractors had been killed in the airstrikes. A Kurdish militia commander and an ex-Russian officer also claimed Russian private military contractors (PMCs) were present and suffered casualties during the strikes. During the two weeks following the incident, U.S. Secretary of Defense Jim Mattis and other U.S. military officials repeatedly stated that U.S. military commanders were in contact with their official Russian counterparts prior to, during, and after the clash and the U.S military were told by their Russian counterparts that there were no Russians in the paramilitary formation.

On 13 February, unclassified footage depicting the coalition's targeted airstrikes on a pro-government T-72 tank position and a reported Russian contractor artillery position in the Khasham area was released by the U.S. Department of Defense.

Syrian government version
In an official statement that was released by the ISIS Hunters unit of the Syrian military, they had received intelligence that ISIL forces were moving towards Khasham and government forces decided to move from the Euphrates so to cut off ISIL's line of attack. At this point, armed groups were spotted east of Khasham, in SDF-held territory, which then attacked the government's troops. The groups were quickly pushed back. The military claimed that, according to intercepted radio traffic, the groups were partly ISIL and partly Kurds, and retreated towards the Conoco factory. At this point, pro-government units were hit by air-strikes. According to Syrian military sources, some 55 pro-government fighters were killed, including around 10 Russian fighters.

Der Spiegel and SOHR version
Three weeks after the incident, Germany′s Der Spiegel published their own investigative report based on evidence gleaned from multiple first-hand sources (participants and witnesses) in the area, which concluded that the ferocious American response was primarily triggered by a unit of Syrian tribal militia and Shiite fighters moving from the town of Al Tabiyeh towards Khasham late on 7 February, concurrently with another group of pro-government forces that had crossed the Euphrates River near the Deir ez-Zor Airport advancing towards Khasham from the village of Marrat. According to Der Spiegel′s report, no Russians were in either formation; yet there was a small contingent of Russian PMCs stationed in Al Tabiyeh, who were not participating in the fighting. Notwithstanding that, between 10 and 20 of the Russians were killed in the U.S. strikes, while most of the formations' deaths were among the servicemen of the 4th Division of the Syrian Army.

Similarly, the UK-based Syrian Observatory for Human Rights reported that 68 pro-government fighters were killed during the day in the area, including 45 who died in the coalition airstrikes, with most being Syrians. The remaining 23 pro-government personnel, including 15 Russians PMCs, were not killed in the airstrikes, but instead caught in a booby-trapped explosion at an arms depot at Al Tabiyeh. The PMCs were accompanying government forces as they advanced towards the SDF-held oil and gas fields.

Unofficial Russian sources version
Shortly after the strikes, various Russian unofficial sources began to publicize information that a number of Russian "volunteers" (PMCs) had been killed in the strikes, with some posts on Russian social media making claims of over 200 Russian PMCs being killed, although the veracity of this information was questioned and could not be confirmed. A Russian paramilitary chief, a known critic of the company that hired the contractors, also claimed 218 PMCs were killed and that the families were still waiting for their remains. Additionally, a Russian military doctor, a leader of a PMC-linked paramilitary Cossack organization and a source with ties to Wagner claimed 80–100 PMCs were killed and 200 wounded.

Contrary to the claims of hundreds of deaths among the PMCs, a Russian investigative group, the Conflict Intelligence Team (CIT), confirmed 10 contractor deaths and estimated a total of between 20 and 30 had died. A Russian journalist also believed between 20 and 25 PMCs died in the strikes. On 17 February, a Wagner leader, Andrey Troshev, was quoted as saying 14 ″volunteers″ died in the battle. Three other Wagner commanders also stated the claim of 200 dead was an exaggeration and that 15 PMCs were killed at the most.

A Russian newspaper, citing Russian military and contractor sources, reported pro-government forces were attempting to capture the Conoco (locally called Al Tabiyeh) gas field from the SDF.

Ukrainian report on casualties
The Security Service of Ukraine (SBU) claimed 80 PMCs were killed in the strikes, naming 50 of them as well as 30 who were wounded, although at least six of the named fatalities were previously confirmed killed in Syria at later dates. Of those named by the SBU as having been killed in the strikes, five were Ukrainian citizens and one was an Armenian.

Official reaction

 * 🇺🇸 - Senator Tim Kaine, Democrat from Virginia, stated in the wake of the attack, "I am gravely concerned that the Trump administration is purposefully stumbling into a broader conflict, without a vote of Congress or clear objectives."
 * 🇷🇺 - Russian member of parliament Franz Klintsevich called U.S. strikes illegal and an act of aggression. Russia has accused the United States of being motivated by the presence of oil in the area. Vassily Nebenzia, Russia's ambassador to the United Nations, called the strikes "regrettable" and promised to raise it to the Security Council. On 8 February 2018, the Russian foreign ministry spokesperson, without referring to the U.S. strike, spoke of ″the US military presence in Syria present[ing] a serious challenge to the peace process and thwart[ing] the protection of the country's territorial integrity.″
 * 🇸🇾 - The Syrian foreign ministry wrote to the United Nations calling for the international community to condemn U.S. actions and labeled them as a war crime, a "brutal massacre," and a crime against humanity. The Syrian government also accused American forces of aiding terrorism and violating Syria's sovereignty.
 * 🇮🇷 - Ali Khamenei strongly condemned the confrontation and stated "Today, the U.S. government is the cruelest and most merciless system in the world, which is even worse than the savage ISIS members."

Political ramifications in Russia and beyond
In the wake of the incident, in absence of any official comments in response to allegations about Russian fatalities, details about Russian citizens′ involvement and casualties in the U.S. strike began to be made public through social and mass media, provoking resentment and outrage from sections of the Russian public. The issue gained additional sensitivity in Russia in view of the upcoming presidential election in March 2018. Prominent among those figures who were early on publicising information about presumably high numbers of Russian casualties in the U.S. strike was Igor Strelkov, who in late February 2018 was registered as an authorized representative of Sergey Baburin, the leader of the nationalist Russian All-People's Union and a candidate for the 2018 Russian presidential election.

Bloomberg, as well as other commentators, opined that both the Russian government and the Trump administration in their official statements appeared to seek to obfuscate any role of the Russian government in the incident. Irek Murtazin of Novaya Gazeta and analyst Yury Barmin speculated that the Russian military command (the MoD) might have wittingly let the Wagner unit find itself in harm's way.

On 12 February 2018, Grigory Yavlinsky called on president Vladimir Putin to present an account of whether any Russian military forces have been involved in the battle. Meanwhile, Russia′s government-run news agency TASS acknowledged, with reference to a Cossack organisation, the death in a battle near Deir ez-Zor of a Russian ″volunteer″, sotnik Vladimir Loginov, a resident of the Kaliningrad Region. The news media also identified by name four more Russians killed during the strike, including Kirill Ananiev, a veteran member of the banned National Bolshevik Party. News outlets also noted that Vladimir Putin abruptly cancelled most of his previously announced engagements scheduled for 12 and 13 February, his press service citing his ill health, and instead had a secret conference with his top military chiefs; he also had a telephone conversation with U.S. president Donald Trump on 12 February, with no details revealed.

Russian politician and an authorised representative of the Communist Party's candidate for the 2018 Russian presidential election Pavel Grudinin, Viktor Alksnis, speaking on the radio, voiced an opinion that the U.S. strike was designed as a demonstration of the U.S.′ military superiority as well as their dominance in the region and might have serious geopolitical consequences for Russia.

On 14 February, the presidential spokesman Dmitry Peskov admitted the possibility of some Russian citizens being in Syria, who were not part of Russia′s armed forces, but dismissed reports of mass casualties as false. The following day, the Russian foreign ministry′s spokesperson Maria Zakharova conceded that five Russian citizens might have been killed in the U.S. attack; she emphasized that these persons were not members of the Russian Armed Forces.

Chairman of the State Duma Defense Committee Vladimir Shamanov, citing reported casualties among Russian PMCs, said the Russian parliament was working on a bill that would legally regulate activities of private military contractors, which he said was necessary.

On 16 February, Viktor Alksnis said that the preliminary figure of Russian fatalities in the strike, based on information from the relatives and friends, stood at 334, mainly the personnel of the 5th storm squadron; he also said that, according to his information, personnel of Russia′s Special Operations Forces were also involved in ″the raid″ on 7 February. This was in contrast to CIT's earlier confirmation by name of no more than eight dead. On the same day, Russian Foreign Minister Sergey Lavrov during Euronews channel interview said, ″[The United States] seem to be seeking to isolate a vast part of the Syrian territory from the rest of the country in violation of Syria's sovereignty and territorial integrity.″ According to an insider source quoted on 19 February by Vedomosti, there were 50 citizens of Russia and Ukraine dead as a result of the U.S. strike.

On 20 February 2018, the Russian foreign ministry released a statement which while admitting that there had been citizens of Russia and ″countries of the CIS″ killed and wounded in the course of the ″recent clash" in Syria, no Russian service members or their materiel had in any way been involved. Following this statement, the foreign ministries of Belarus and Kazakhstan were reported to be checking if there were casualties among their countries′ citizens, but stated they had no information that confirms Belarusians or Kazakhstanis had been killed or wounded.

In late February 2018, CNN quoted multiple Russian sources as claiming that those who sought to publicise information about the casualties in the 7 February strike were being harassed and hushed presumably by people loyal to Yevgeny Prigozhin.

Several Russian online news outlets, with a reference to Syria′s media as well as ex-KGB officer Igor Panarin, publicised unconfirmed reports that the Su-57 fighters, which were in February 2017 deployed to Syria, had taken part in strikes against rebel targets in Eastern Ghouta killing about ten U.S. personnel (military instructors) as well as other Western countries′ instructors stationed in the rebel stronghold; the strikes were presented as retaliation for the U.S. attack at Khasham. A short-term deployment of two Su-57s to Syria was confirmed by the Russian defence minister Sergey Shoygu on 1 March 2018; earlier, military correspondent of Komsomolskaya Pravda Viktor Baranets was cited as saying that according to his information the Su-57s had "excellently" carried out their mission in Eastern Ghouta.

On 12 April 2018, outgoing U.S. Central Intelligence Agency director Mike Pompeo, during his Senate hearing for the position of the United States Secretary of State, commented, "This administration announced a nuclear posture review that has put Russia on notice that we are going to recapitalize our deterrent force. In Syria, now, a handful of weeks ago the Russians met their match. A couple hundred Russians were killed."

The death of the Russian investigative journalist Maksim (Maxim) Borodin who wrote about the deaths of mercenaries in Syria in mid-April 2018 was linked by media to his publications about the Wagner Group′s casualties in the clash at Khasham.

Further incidents in the area
On 10 February 2018, a U.S. MQ-9 Reaper drone destroyed a T-72 tank of pro-government forces in an air strike near the Al Tabiyeh gas field. The tank itself was not firing on the SDF and the coalition, but other elements in the formation were.

On 2 March 2018, at least two pro-government fighters were reportedly killed by coalition air raids near Khasham.

On 27 March 2018, U.S. officials, including U.S. Secretary of Defense James Mattis, said a contingent of pro-Syrian government forces and Russian "mercenaries" had again similarly amassed near coalition forces in Deir ez-Zor the week prior, but the potential confrontation was this time defused after the U.S. military contacted Russian officers. Mattis believed the forces were under Russian control, as the pro-government troops pulled back after U.S. forces spoke with their Russian counterparts.

On 29 April 2018, pro-government forces launched an assault against four SDF villages on the Euphrates, initially capturing them. However, the SDF later retook the villages, with local sources claiming U.S.-led coalition aircraft bombed pro-government positions in response.

On 11 May 2018, the U.S.-led coalition stated that SDF units responded to artillery fire from an unknown source on the outskirts of Deir ez-Zor; the SDF returned fire, leading to the destruction of one enemy artillery piece. No casualties were reported on either side of the engagement. The coalition discussed the development with Russian counterparts along established "deconfliction" lines.