Russia has said it is suspending a deal with the US to prevent mid-air collisions over Syria in response to US air strikes on a Syrian air base.

The Russian Foreign Ministry said following Donald Trump's decision to fire 59 cruise missiles at a military target in Syria on Thursday, Moscow was suspending a memorandum with the US that prevented incidents and ensured flight safety.

Under the memorandum, signed after Russia launched an air campaign in Syria in September 2015, Russia and the US had exchanged information about their flights to avoid incidents in the crowded skies over Syria — where Russia has several dozen warplanes and batteries of air-defence missiles.

Footage shows tomahawk missiles being fired at Syria from the U.S Navy

The so-called "deconfliction line" between the US and Russia has been credited by a number of US pilots with helping keep them safe. While the US air campaign in Syria tends to steer clear of areas where Russia is in operation, ending such co-operation is seen by activists in the region as a worrying turn.

The US-side of the information sharing exercise is based in the al-Udeid Air Base in Qatar, which is also the forward base from US Central Command, which takes the lead in co-ordinating coalition strikes. The US maintains radar coverage and other means of scanning the skies, but without being able to share coordinates and other data with the Russians, the chances of a confrontation increases.

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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 read: "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."

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The country's Defence Ministry said that Syrian air defences would be beefed up following the US strikes, with Russian news agencies reporting that the ministry had also mocked the effectiveness of the strikes as "extremely low" claiming that only 23 of the missiles had hit their target.

Russian Foreign Minister Sergey Lavrov meanwhile said Moscow would demand an explanation from the US over the air strikes, describing the attack as "an act of aggression with an invented pretext”, and adding that he hoped the "provocation" would not lead to irreparable damage to Russia's ties with the US.

In pictures: US missile strike against Syria Show all 7 1 /7 In pictures: US missile strike against Syria In pictures: US missile strike against Syria The guided-missile destroyer USS Porter (DDG 78) launches a tomahawk land attack missile in the Mediterranean Sea AP In pictures: US missile strike against Syria The United States military launched at least 50 tomahawk cruise missiles at al-Shayrat military airfield near Homs, Syria, in response to the Syrian military's alleged use of chemical weapons in an airstrike in a rebel held area in Idlib province EPA In pictures: US missile strike against Syria Shayrat airfield in Syria Getty Images In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria President Donald Trump speaks at Mar-a-Lago in Palm Beach, Fla., after the US fired a barrage of cruise missiles into Syria in retaliation for this week's gruesome chemical weapons attack against civilians AP In pictures: US missile strike against Syria Syria's President Bashar al-Assad Reuters

The cruise missile strikes launched from US ships in the Mediterranean have killed six Syrian troops and led to big material losses, according to the Syrian Army, which has described the attack as a "blatant act of aggression". No Russians were killed in the air strikes, Mr Lavrov said, with the Russians claiming four Syrian military personnel being killed in the strikes, while two were missing and six were injured.

The White House described the attack as a “warning shot” that was “necessary and appropriate” following Mr al-Assad’s alleged use of chemical weapons on civilians in rebel-held town Idlib earlier this week.