When were the missiles launched and what was the target?
The US fired 59 Tomahawk cruise missiles from the warships USS Ross and Porter in the eastern Mediterranean in the early hours of Friday morning Syrian time.
They hit the Shayrat airbase in central Syria, near the city of Homs. The US had identified the base as the location used to launch Tuesday’s chemical attack on the rebel-held town of Khan Sheikun that killed more than 80 people.
Syrian and Russian forces used the base. Russians first deployed there in the autumn of 2015, when they reportedly reinforced some facilities.
Why did the US use the Tomahawk?
Launched from ships or submarines and with a range of more than 1,000 miles, Tomahawk missiles have been at the heart of the US arsenal for more than two decades. They were first used in the 1991 Gulf war, when nearly 300 were deployed.
They carry fewer explosives than drones or manned planes, but their GPS system allows the military to keep pilots and aircraft away from dangerous airspace.
More than 6.25 metres long (20ft) and weighing 1,590kg (3,500lb), the Tomahawk is billed by the US navy as “an all-weather, long range, subsonic cruise missile”.
They are designed to fly at low altitudes towards even heavily defended land targets with extreme accuracy, usually carrying warheads of up to 454kg (1,000lb).
How much damage did they cause?
Moscow was told of the strikes in advance, and no Russian forces or equipment were hit in the strike. There were reports that senior Syrian officers also evacuated the base.
The Pentagon said its missiles had targeted aircraft, shelters, fuel storage and other logistics buildings, air defence systems, radars and ammunition supply bunkers. The attack was said to be over in a couple of minutes.
Syria’s military said seven people were killed and several wounded. Six Syrian air force planes undergoing repairs at the base were destroyed, but the runways were undamaged, the Russian defence ministry said after the attack.
The attack planners took care to avoid hitting suspected chemical weapons stores on the base, the US national security adviser, HR McMaster, said.
Will the airstrikes affect Syrian military capacity?
The actual damage caused by the airstrikes seems to be relatively limited – it appears to be a warning over the use of chemical weapons rather than an attempt to scale back or disable Syrian air capacity.
The Syrian government controls over a dozen airbases, and has a large fleet of planes and helicopters, even after years of war. It also has the backing of the Russian military and its air force.
On Friday Moscow promised to help bolster Syrian air defences, “to protect Syria’s most sensitive infrastructure” and presumably deter any future strikes.