Jim Muir writes: As happened in Iraq, intervention by the West risks fragmenting the country further, creating an uncontrollable situation and handing large parts of it to forces it regards as its enemies.

To that extent, there may be more common ground between Washington and Moscow than meets the eye.

The Russians, traumatised by Chechnya, are also mesmerised by the prospect of a radical Islamist takeover in Syria.

That is why some observers believe there is still a measure of understanding between the Russians and Americans, whose foreign ministers decided in May to work together to bring about the political settlement that everybody agrees is the only solution, but which is proving devilishly difficult to get under way.

So it is not out of the question that the huge pressures exerted on all parties by the chemical weapons attacks might just be enough to pop the cork and force movement towards negotiations, with the latest speculation focusing on Geneva in October.

Any such prospect, distant though it may seem, would clearly be set back by Western military action.