Did Russia warn Assad about Trump's missile strike?

Russian military staff at a Syrian regime airbase attacked by the US were given advance warning of the military action that took place, the Pentagon confirmed Friday.

The revelation opens the possibility that the Russian military personnel passed on the information their Syrian counterparts.

"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," spokesperson Captain Jeff Davis said on Friday. 

The US attack on the airbase killed 16 people, Syria's state-owned SANA news agency said.

US navy vessels fired 59 Tomahawk missiled at the Shayrat airbase near Homs at dawn on Friday.

The attack, US President Donald Trump explained, was in retalitation for the chemical attack perpetrated by the Syrian regime on a rebel-held village.

Russia, a long standing ally of President Bashar al-Assad, responded by threatening to boost its air defences in Syria and sever communication with US forces.

Moscow blasted the attack as "an aggression under fake pretence" and said it was in violation of international law.

The Trump administration's decision to launch its first direct attack on Syria's regime marks a signifacant development in US policy on Syria and its embattled dictator.

Trump's predecessor Barack Obama had previously warned that the use of chemical weapons would cross a "red line" that would necessitate intervention, however did not go as far as the US action taken early on Friday.