The US fired Tomahawk missiles at a Syrian military base on Friday in response to the chemical weapon attack over Idlib province earlier this week.
The US Department of Defense said the air strike was "in retaliation for the Assad regime using nerve agents against its people."
Four Syrian military officers had been killed in the attack, which has been condemned by Russia as "aggression against sovereign state". Australia, UK and Turkey expressed support for the air strike. China urged the avoidance of "further deterioriation" in the situation in Syria, AFP reported.
The US' action came after the UN Security Council failed to reach an agreement on taking action over the chemical weapons attack.
Pentagon spokesperson Captain Jeff Davis confirmed that Russia was informed of the attack in order to ensure Russian forces were not targetted.
"Russian forces were notified in advance of the strike using the established deconfliction line. US military planners took precautions to minimise risk to Russian or Syrian personnel located at the airfield," he said.
"We are assessing the results of the strike. 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."
This is the first direct US air strike on Syria since 2011.