Russia, Iran to use force if US crosses 'Red Lines' again

Russia and Iran have warned the US they will "respond with force" if their own "red lines" are crossed in Syria.

Following Friday's cruise missile strike on a Syrian air base, in retaliation for the chemical attack on Khan Sheikhoun earlier in the week, the alliance supporting Syrian President Bashar al-Assad made a joint statement threatening action in response to "any breach of red lines from whoever it is".

"What America waged in an aggression on Syria is a crossing of red lines. From now on we will respond with force to any aggressor or any breach of red lines from whoever it is and America knows our ability to respond well," the group's joint command centre said.

US President Donald Trump said the strike with some 60 Tomahawk missiles on al Shayrat air base, near Homs, was "representing the world". The base was allegedly used by Syrian forces to conduct the attack, which killed more than 80 people.

On Sunday the UK's Defence Secretary, Sir Michael Fallon, demanded Russia rein in Assad, claiming that Moscow is "responsible for every civilian death" in Khan Sheikhoun.

Sir Michael said the attack had happened "on their watch" and that Vladimir Putin must now live up to previous promises that Assad's chemical weapons had been destroyed.

Experts have dismissed Russia's claim that a rebel chemical weapons facility caused the deaths. Britain, the US and France accused Assad's regime of gassing civilians in the opposition-held town, but Damascus claimed it destroyed its toxic stockpiles following an international agreement struck in 2013.

The Russian defence ministry put out a competing version of events claiming legitimate Syrian air strikes against "terrorists" had struck a warehouse used to produce and store shells containing toxic gas, which were allegedly being sent to Iraq.

The joint command centre also said on Sunday the missile strike would not deter it from "liberating" Syria, and that the US military presence in the north of the country amounted to an illegal "occupation".

Putin and Iranian leader Hassan Rouhani have called for an objective investigation into the chemical attack.

The army chiefs of Russia and Iran discussed the US strikes in Syria by phone on Sunday, and vowed to continue the fight against "terrorists" and their supporters, Iranian media reported.

The two chiefs of staff, Major General Mohammad Bagheri and General Valery Gerasimov, "condemned the American operation against a Syrian air base which is an aggression against an independent country", state news agency IRNA said.