SENIOR American military officials have launched a probe to find out if Russia was involved in the deadly chemical weapons attack in Syria and a Russian warship is sailing for the Mediterranean as tensions rise following the US missile strike on a Syrian air base.

Sources at the Pentagon say officials are studying reports that a hospital where casualties from the suspected nerve gas attack were taken was later scoped by a drone belonging either to Russia or Syria and bombed in an apparent bid to cover up evidence.

In response to Friday morning's strike on the Shayrat air base, Russia has said it is suspending a deal with the US to prevent mid-air collisions over the war-torn country and has sent a frigate to the Syrian coast.

Missile attack fallout: Timeline of accusations, denials and warnings

Under the memorandum, signed after Vladimir Putin launched an air campaign in September 2015, Russia and the US had exchanged information about their flights to avoid incidents in the crowded skies over Syria,

Officials have warned that Russia has failed to control the Syrian government's use of chemical weapons, and have said that the US "will no longer wait" for them to be used by the Assad regime.

It has been reported that the American intelligence service believes Russian personnel were at air base when Sarin nerve gas was loaded on to a Syrian jet, but they have not established whether the Russians knew it was happening.

Speaking during a tense emergency meeting of the UN Security Council yesterday, The US ambassador to the UN, Nikki Haley, said: "The United States took a very measured step last night. We are prepared to do more. But we hope that will not be necessary."

"Assad did this because he thought he could get away with it. He thought he could get away with it, because he knew Russia had its back."

"The moral stain could no longer be unanswered. His crimes against humanity could no longer be ignored."

Missile attack fallout: Timeline of accusations, denials and warnings

"The US will no longer wait for Assad to use weapons with no consequences. Those days are over."

Syria, for its part, has condemned the strike, which left a number of people dead. The office of President Bashir Assad called the strike "reckless" and "irresponsible".

Four children are reported to be among nine civilians killed in the "targeted assault", while six servicemen are believed to have also been killed.

The statement said the missile strike was "short-sighted" and reflected a policy, regardless of which administration, which is based on targeting and "subjugating people".

Syrian State TV also said the bombing was an "aggression", although the opposition welcomed the military action.

The US strike followed Tuesday's gruesome chemical attack in the town of Khan Sheikhoun, where more than 80 people were killed.

Initial reports said about 60 US Tomahawk missiles hit the base south-east of Homs, a small installation with two runways, where aircraft often take off to bomb targets in northern and central Syria.

Missile attack fallout: Timeline of accusations, denials and warnings

However, Russian defence ministry spokesman Major General Igor Konashenkov claimed that "the combat efficiency of the US strike was very low", adding that only 23 of the 59 Tomahawk cruise missiles reached the base.

He said it destroyed six MiG-23 fighter jets of the Syrian air force which were under repair, but did not damage other Syrian warplanes at the base. He added that the base's runway was left undamaged.

Major General Konashenkov also said the Russian military will help Syria beef up its air defences following the US strike.

Russia has ordered The Admiral Grigorevich, a cruise missile-carrying frigate, to abandon joint exercises in the Black Sea with the Turkish navy and sail for the Syrian coast.

Missile attack fallout: Timeline of accusations, denials and warnings

Russian President Vladimir Putin, a staunch ally of Syrian President Bashar al-Assad, condemned the US strikes near Homs, saying they broke international law and have seriously damaged US-Russia relations.

A statement from the Russian Foreign Ministry said: "The very presence of US troops and other countries on the territory of Syria, without the consent of the Government or the decision of the UN Security Council is a gross, obvious and unwarranted violation of international law.

"If before it was due to the task of combating terrorism, now there is a clear act of aggression against a sovereign Syria. US Actions taken today further destroy the Russian-American relations.

He said that a "complex of measures" to strengthen Syrian air defences will be done shortly to help "protect the most sensitive Syrian infrastructure facilities".

Missile attack fallout: Timeline of accusations, denials and warnings

Announcing the strike, US President Donald Trump said that Assad "choked out the lives of helpless men, women and children".

"Even beautiful babies were cruelly murdered in this very barbaric attack."