On the morning of 7 April 2017, the United States launched 59 Tomahawk cruise missiles from the Mediterranean Sea into Syria, aimed at Shayrat Airbase controlled by the Syrian government. The strike was executed on the authorization of U.S. president Donald Trump, as a direct response to the Khan Shaykhun chemical attack that occurred on 4 April.
The strike was the first unilateral military action by the United States targeting the Syrian government during the Syrian civil war. President Trump stated shortly thereafter, "It is in this vital national security interest of the United States to prevent and deter the spread and use of deadly chemical weapons."
The Syrian Air Force launched airstrikes against the rebels from the base only hours after the American attack. It was reported that advance warning was given to Russia, an ally of the Syrian government, by the US prior to the missile strike.
On the evening of 6 April, President Trump notified members of the U.S. Congress of his plan on the missile strike. According to a White House official, more than two dozen members of Congress were briefed at the notification. Internationally, the United States also notified several countries, including Canada, the UK, Australia, and Russia, in advance of the strike. The U.S. military stated it communicated with the Russian military to minimize any chance of Russian casualties. The strike was conducted without either U.S. congressional or United Nations Security Council approval. Commodore Tate Westbrook commanded the Navy task force in charge of the missile launch.
It was the first time that the United States had acknowledged intentionally carrying out military action against the forces of Syrian president Bashar al-Assad.
The strike targeted Shayrat Airbase in the Homs Governorate, which was believed by U.S. intelligence to be the base for the aircraft that carried out a chemical weapons attack on 4 April, and was intended to destroy air defenses, aircraft, hangars and fuel. The US avoided striking a suspected sarin gas storage facility at the targeted airport. Fifty-nine Tomahawk missiles were said to have been launched from two U.S. Navy warships, USS Ross and USS Porter, at around 20:40 EDT (04:40 local time). Reconnaissance was provided by Python 73, a Boeing RC-135 of the 55th Wing.
U.S. Central Command stated in a press release that Tomahawk missiles hit "aircraft, hardened aircraft shelters, petroleum and logistical storage, ammunition supply bunkers, defense systems, and radars". Initial U.S. reports claimed "approximately 20 planes" were destroyed, and that 58 out of the 59 cruise missiles launched "severely degraded or destroyed" their intended target. According to the satellite images the runways and the taxiways have been reportedly undamaged and combat flights from the attacked airbase resumed on 7 April a few hours after the attack, although U.S. officials did not state that the runway was a target. In a later statement on 10 April 2017, the US secretary of defense James Mattis claimed that the strike destroyed about 20% of the Syrian government's operational aircraft and the base had lost the ability to refuel or rearm aircraft.
An independent bomb damage assessment conducted by ImageSat International counted hits on 44 targets, with some targets being hit by more than one missile; these figures were determined using satellite images of the airbase 10 hours after the strike. Among the targets struck was a 2K12 Kub (SA6) missile battery composed of five elements.
The Syrian Observatory for Human Rights said the strike damaged over a dozen hangars, a fuel depot, and an air defense base.
Al-Masdar News reported that 15 fighter jets were damaged or destroyed and that the destruction of fuel tankers caused several explosions and a large fire.
According to the claims of Russian defense ministry, the "combat effectiveness" of the attack was "extremely low"; they claimed that only 23 missiles hit the base destroying six aircraft, and it did not know where the other 36 landed. Russian television news, citing a Syrian source at the airfield, said that nine planes were destroyed by the strikes (5 Su-22M3s, 1 Su-22M4, and 3 Mig-23ML) and that all planes were thought to have been out of action at the time. The Israeli satellite imagery services company ImageSat International later released high resolution satellite images of the base taken within 10 hours of the attack showing that at a minimum, 44 targets had been hit, and that some had been hit multiple times.
Seven or nine Syrian soldiers were killed, including a general; Russian military personnel were also present at the airbase at the time it was attacked. According to Syrian state news SANA, nine civilians were also killed in the attack, including four children. SANA also stated that five of the civilians were killed in the village of Shayrat, outside the base, while another four were killed in the village of Al-Hamrat, and that another seven civilians were wounded when a missile hit homes in Al-Manzul, four kilometers (two and a half miles) away from the Shayrat air base. According to Russian defense ministry spokesperson Igor Konashenkov, four Syrian soldiers were killed and another two were missing.
Some observers believe that the Russian government warned the Syrian government, which had enough time to move planes to another base.
Hours after the U.S. missile strike, Syrian military aircraft took off from the Shayrat base to attack rebel positions again, including the town of Khan Shaykhun. Commentators attributed the ability of the Syrian government to continue to operate from the base to the fact that the US gave Russia, Syria's ally, an advanced warning regarding the strike, which enabled Syrians to shelter many of its aircraft from the attack.
Within a day of the attack, Russia announced it would strengthen Syria's air defenses and formally notified the Pentagon that as of 21:00 GMT (00:00 Moscow Time, 8 April 2017), Russia had suspended the U.S.–Russia Memorandum of Mutual Understanding, which had established a hotline between the countries' militaries designed to avoid collisions between their aircraft over Syria. As a result, Belgium suspended its air operations in Syria, and the US began limiting itself to only the most essential air strikes.
According to some local sources, the Islamic State of Iraq and the Levant took advantage of the attack and absence of the Syrian Air Force in eastern Homs, by launching several attacks on the Syrian Army's defenses in the western Palmyra countryside. It also attacked the checkpoints outside the village of al-Furqalas, but those attacks were repelled. According to the Syrian Observatory for Human Rights, the Shayrat airbase remained operational and Syrian warplanes took off from it the following day. The price of oil briefly rose over 2% following the strike.
After both the chemical attack and missile strike, the U.S. administration was in disagreement and contradiction to U.S. policy from 2013 until 30 March 2017, as well the statements by U.S. ambassador to U.N. Nikki Haley, United States secretary of state Rex Tillerson, White House press secretary Sean Spicer and National Security Advisor H. R. McMaster differed on the change of U.S. military posture toward Syria and prioritization of regime change.
On 7 April 2017, an emergency meeting of the United Nations Security Council was held: Bolivia's ambassador Sacha Llorenty requested a closed session to discuss the U.S. strike, but U.S. ambassador Nikki Haley, serving as the council president for April, forced the meeting to be held in public view. United Nations News Centre reported that while some delegates expressed support for the strikes as a response to the Syrian government's alleged use of chemical weapons, others condemned it as a unilateral act of aggression, underlining that the Council must authorize any such intervention.