Syrian troops have been killed in US missile strikes on a government air base thought to be the source of a devastating chemical attack. Here are the latest updates:

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Dozens of cruise missiles were fired from two American warships stationed in the Mediterranean Sea in the early hours of Friday morning.

They hit Shayrat air base in the province of Homs, killing at least six of Bashar al-Assad’s troops and destroying planes, helicopters, ammunition stores and buildings.

“Initial indications are that this strike has severely damaged or destroyed Syrian aircraft and support infrastructure and equipment at Shayrat airfield, reducing the Syrian government's ability to deliver chemical weapons,” said Pentagon spokesman Captain Jeff Davis.

Trump orders missile strike on Syria after chemical weapon attack on civilians

In pictures: US missile strike against Syria Show all 7 1 /7 In pictures: US missile strike against Syria In pictures: US missile strike against Syria The guided-missile destroyer USS Porter (DDG 78) launches a tomahawk land attack missile in the Mediterranean Sea AP In pictures: US missile strike against Syria The United States military launched at least 50 tomahawk cruise missiles at al-Shayrat military airfield near Homs, Syria, in response to the Syrian military's alleged use of chemical weapons in an airstrike in a rebel held area in Idlib province EPA In pictures: US missile strike against Syria Shayrat airfield in Syria Getty Images In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria President Donald Trump speaks at Mar-a-Lago in Palm Beach, Fla., after the US fired a barrage of cruise missiles into Syria in retaliation for this week's gruesome chemical weapons attack against civilians AP In pictures: US missile strike against Syria Syria's President Bashar al-Assad Reuters

The Assad government and its Russian allies have denied civilians were gassed in the rebel-held town of Khan Sheikhoun, where up to 100 people died on Monday.

The World Health Organisation, Turkish analysts and doctors concluded that sarin was used, a nerve agent banned as a weapon of mass destruction under international law.

Donald Trump announced he had ordered the attack, calling Assad a “dictator” who had “launched a horrible chemical weapons attack on innocent civilians”.

“Tonight I ordered a targeted military strike on the airfield in Syria from where the chemical attack was launched,” the President added.

"It is in this vital national security interest of the United States to prevent and deter the spread and use of deadly chemical weapons.”

In pictures: US missile strike against Syria Show all 7 1 /7 In pictures: US missile strike against Syria In pictures: US missile strike against Syria The guided-missile destroyer USS Porter (DDG 78) launches a tomahawk land attack missile in the Mediterranean Sea AP In pictures: US missile strike against Syria The United States military launched at least 50 tomahawk cruise missiles at al-Shayrat military airfield near Homs, Syria, in response to the Syrian military's alleged use of chemical weapons in an airstrike in a rebel held area in Idlib province EPA In pictures: US missile strike against Syria Shayrat airfield in Syria Getty Images In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria President Donald Trump speaks at Mar-a-Lago in Palm Beach, Fla., after the US fired a barrage of cruise missiles into Syria in retaliation for this week's gruesome chemical weapons attack against civilians AP In pictures: US missile strike against Syria Syria's President Bashar al-Assad Reuters

Critics voiced their shock over the abrupt decision, days after senior American officials said Assad’s removal was no longer a priority, and pointed at Mr Trump’s previous assertions that a President would have to get Congressional approval to attack Syria.

A spokesman for Vladimir Putin said the strike had seriously damaged ties between Washington and Moscow, which has been supporting the Syrian regime with its own air strikes.

The Russian President regards the strikes as an “aggression against a sovereign nation” on a “made-up pretext” and a cynical attempt to distract the world from civilian deaths in Iraq, said his spokesman Dmitry Peskov.

It is the only direct action against the Syrian government taken by the US in the six-year civil war, where international attention has increasingly been drawn to the threat of Isis.

US officials said they informed Russian forces ahead of the missile attacks and avoided hitting Russian troops at the base, but did not seek the Kremlin’s approval.

The attack was a “one-off,” a US defence official told Reuters, meaning it was expected to be a single strike with no current plans for escalation.

Syrian state television hit out at “American aggression”, while Assad’s ally Iran also denounced the attack as a “destructive violation of international law”.