The US has fired dozens of cruise missiles at a Syrian airbase from which it said a deadly chemical weapons attack was launched this week, an escalation of the US military role in Syria that swiftly drew sharp criticism from Russia.
Two US warships fired 59 cruise missiles from the eastern Mediterranean Sea at the Syrian airbase controlled by forces of President Bashar al-Assad in response to a poison gas attack in a rebel-held area on Tuesday, US officials said.
Facing his biggest foreign policy crisis since his January 20 inauguration, President Donald Trump took the toughest direct US action yet in Syria's six-year-old civil war, raising the risk of confrontation with Russia and Iran, Assad's two main military backers.
Russian President Vladimir Putin believes that the missile strikes on a Syrian air base broke international law and have seriously hurt US-Russia relations, news agencies cited the Kremlin as saying.
The Russian leader regarded the US action as "aggression against a sovereign nation" on a "made-up pretext" and as a cynical attempt to distract the world from civilian deaths in Iraq, Putin's spokesman Dmitry Peskov was cited as saying.
US officials said they informed Russian forces ahead of the missile attacks and that they took pains to avoid hitting Russian troops at the base, saying there were no strikes on sections of the base where Russians were present. But they said the administration did not seek Moscow's approval.
"Years of previous attempts at changing Assad's behaviour have all failed and failed very dramatically," Trump said as he announced the attack from his Florida resort, Mar-a-Lago, where he was meeting Chinese President Xi Jinping.
Trump ordered the strikes a day after he blamed Assad for this week's chemical attack, which killed at least 70 people, many of them children, in the Syrian town of Khan Sheikhoun. The Syrian government has denied it was behind the attack.
The Tomahawk missiles were launched from the USS Porter and USS Ross around 8.40 pm EDT (3.40pm Syrian time), striking multiple targets - including the airstrip, aircraft and fuel stations - on the Shayrat Air Base, which the Pentagon says was used to store chemical weapons.
"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.
At least four Syrian soldiers, including a senior officer, were killed in the attack, which almost completely destroyed the base, the Syrian Observatory for Human Rights said.
The US cruise missile 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.
The attacks spurred a flight to safety in global financial markets, sending yields on safe-haven US Treasury securities to their lowest since November.