British Prime Minister David Cameron, "sickened" by images of children suffering after a chemical attack outside of Damascus, wants to convene an emergency session of the Security Council and issue an ultimatum to Syrian President Bashar Assad; disarm or suffer the consequences.

Telegraph:

The Prime Minister spoke with President Barack Obama by telephone to ask for help with convening an emergency session of the United Nations Security Council.

The Prime Minister is also to hold a meeting of the National Security Council. However, senior military figures have said privately that the "window of opportunity" for a successful intervention in Syria has long been closed.

But US officials were studying the Kosovo conflict, in which Nato launched weeks of air strikes without UN support and in the teeth of Russian opposition.

He wants to put forward a "game-changing" resolution that would give the Syrian government, led by Bashar al-Assad, "one last chance" to disarm.

Mr Cameron is said to have been left sickened by images of children killed by the chemical weapons.

One charity yesterday said at least 355 people had died and 10 times that number were treated for poisoning.

Britain and France have blamed the Assad regime for the chemical attack.

On Saturday night four American destroyers were moving closer to Syria, armed with Tomahawk cruise missiles, which are capable of precision strikes.

Gen Sir Nick Houghton, the Chief of the Defence Staff, is to take part in a summit in Jordan tomorrow with his US, French, Turkish, Saudi Arabian and Qatari counterparts.

It follows the strongest indications to date from Washington that direct military intervention by the West was possible in the conflict.

Diplomats talked of a "change in the American posture" following the attack on the suburb of East Ghouta on Wednesday.

Mr Cameron's officials were drafting the text of a resolution to put before the UN said to be modelled on one that offered Saddam Hussein, the late Iraq leader, "a final opportunity" to disarm in 2002.

The move risks a public row with Vladimir Putin, the Russian president, who does not want any action taken against his ally.

As horrific an attack that it was (and we're still not sure who launched it), Cameron's resolution solves nothing. Because after all is said and done, Cameron is, in effect, volunteering the US for military action. Nobody expects Great Britain to bear the brunt of any intervention. The only nation that can project military power over distance is America, and neither Hollande or Cameron can do much except cheerlead from the sidelines.

Tossing a few cruise missiles at Syrian army bases would be a futile gesture. Only a sustained bombing campaign can degrade Assad's ability to reist the rebels. And if we've decided to take the side of the Islamists, we better be prepared to fight al-Qaeda in Syria as well as Iraq.

The computer in "War Games" had it right: " A strange game. The only winning move is not to play."