Russia plans to increase air defences in Syria after a US missile strike on a government-controlled airfield, warning the military action had made the risk of conflict “significantly higher”.

The Russian Defence Ministry said it would be beefing up the Syrian army's ability to shoot down enemy warplanes in the wake of strike.

“To cover the most sensitive objects in Syria’s infrastructure a set of measures will be soon implemented to strengthen and improve the effectiveness of the air defence systems of the Syrian armed forces,” a statement said.

It also mocked the effectiveness of the attack, saying just 23 of the 59 tomahawk cruise missiles fired from US Navy destroyers had hit their target.

The ministry said it was unclear where 36 other missiles had landed.

"The combat effectiveness of the US massive missile attack on the Syrian air base is extremely low," the statement continued.

“These actions of the American side are seen as a flagrant violation of the memorandum signed in 2015 on the prevention of incidents and safety during operations in Syrian airspace.”

Russia’s Black Sea Fleet’s frigate, the Admiral Grigorovich, is now heading for the Syrian port city of Tartus in the eastern Mediterranean, according to sources quoted by Russian news agency Tass.

The vessel was on a routine operation but would head for Tartus. It is armed with Kalibr cruise missiles.

It is not clear if the Russian Defence Ministry was referring to the Admiral Grigorovich in its statement released on Friday morning.

U.S. airstrikes on Syria, explained

Six MiG-23 fighter jets, a radar post, logistics warehouse, educational building, and dining room had been destroyed in the strike, the statement said.

Runways, taxiways and aircraft parking areas of the Syrian Air Force were not damaged, it added.

The ministry also accused the Trump administration of planning a missile strike on Syria long before the alleged chemical attack by President Bashar al-Assad this week.

Loading....

“It is obvious that the impact of American cruise missiles on the Syrian air base was prepared long before today's events,” the statement said.

“The preparation of such a strike is necessary to conduct a large range of activities for exploration, planning, preparation of flight missions and bringing the missiles into full readiness for launch.

“For any specialist it is clear that a decision on the missile strike on Syria was taken in Washington long before the events in the village Khan Sheikhoun.”

Washington, it said, carried out the strike “solely for domestic political reasons”.