UNITED NATIONSinfo-icon: Russiainfo-icon has warned that USinfo-icon cruise missileinfo-icon strikes on Syriainfo-icon could have "extremely serious" consequences, as direct US intervention in the embattled Arab country escalated tensions between Moscowinfo-icon and Washington.

The warships USS Porter and USS Ross in the Mediterranean Sea launched dozens of Tomahawk missiles at the Shayrat air base, President Trumpinfo-icon's biggest foreign policyinfo-icon decision since taking office in January and the kind of direct intervention in Syria's six-year-old civil warinfo-icon his predecessor Barack Obama avoided.

Moscow condemned the strikes as an act of "aggression against a sovereign nation" and a violation of international law.

"We strongly condemn the illegitimate actions by the US The consequences of this for regional and international stability could be extremely serious," Russia's deputy UN envoy, Vladimir Safronkov, told a meeting of the UN Security Council on Friday.

Russian Prime Minister Dmitry Medvedev charged that the US strikes were one step away from clashing with Russia's military.

Satellite imagery suggests the base houses Russian special forces and helicopters, part of the Kremlin's effort to help Syrian armyinfo-icon fight Daesh and other militant groups.

US Secretary of State Rex Tillerson, who is scheduled to go to Moscow next week, said he was disappointed but not surprised by the Russian reaction because it showed continued support for the Syrian government.

Tillerson said the strike took out about 20 percent of the seventh wing of the Syrian air force and hit a fueling facility. The base's runway was still in use.

The Syrian army said the US attack killed six people and called it "blatant aggression" that made the United Statesinfo-icon a partner of "terrorist groups" including Daesh. 

Washington has long backed rebels fighting Syrian army in a multi-sided civil war that has killed more than 400,000 people and driven half of Syrians from their homes since 2011.Russia's defense ministry responded to the attack by calling in the US military attache in Moscow to say that at midnight Moscow time (5pm EDT) it would close down a communications line used to avoid accidental clashes between Russian and US forces in Syria, Interfax new agency said.

Following US's unprecedented offensive, a Russian Foreign Ministry statement said that Moscow was suspending the 2015 air safety agreement with Washington aimed at avoiding mid-air collisions during their military missions in the Syrian airspace.

Hours later, a US-led coalition spokesman confirmed that Russia had notified the alliance of its intent to halt the deal.

Russia has secured its Syrian bases in Hmeimim and Tartus with S-300 and S400 missile defense systems.

Syria's S-200 air defense systems have been restored with Russia's help, TASS reported, adding that those complexes are also deployed to provide protection for the Russian military in eastern Syria.

Meanwhile reports said, Russia sent a missile-armed frigate to its naval base in Syria's Mediterranean coastal city of Tartus following the US strike.

An informed military-diplomatic source in Moscow told Russia's TASS news agency on Friday that the Admiral Grigorovich, a Russian Black Sea Fleet's frigate, was due to arrive in the Mediterranean later on the day.

"The Russian ship armed with cruise missiles Kalibr will visit the logistics base in Tartus," the source said.

The 4,000-ton warship's presence off Syria's coast would depend on the situation, but "in any way it will last more than a month," the source added.

Iraninfo-icon, which is a key backer of Damascuss also condemned the US strike, with President Hassan Rouhani saying it would bring "only destruction and danger to the region and the globe."

The strike drew the praise from anti-Damascus militant groups as well as the parties long viewed as their staunch supporters, including Saudi Arabiainfo-icon, Israel, Turkeyinfo-icon and their Western allies.