Words alone will not end Syria's war of terror

American interests will be engulfed quickly if the crisis in Syria continues spilling over the Syrian border. This should be another "red line" in Barack Obama's calculation.

They now call it America's dilemma, not Syria's. In August last year, US President Barack Obama warned that the use of chemical weapons constituted a "red line" for intervention in Syria. But now that the red line appears to have been crossed, at least according to reports from Britain, Israel and the US, the question for the American president is this: how much longer can he avoid the inevitability of more forceful intervention?

Mr Obama is under great pressure to do more to aid the opposition, and yet he continues to demur. At the weekend he insisted the evidence supporting the use of chemical weapons remains preliminary and that the US would conduct a "vigorous investigation" before considering future action. Chemical weapons deployment would be a "game changer", he said.

Arab allies have sought to support opposition forces with arms and cash, but this has not turned the tide in the opposition's favour. Mr Obama, meanwhile, may rightly gauge that the US public does not see the Syrian war as theirs, but American interests will be engulfed quickly if the crisis in Syria continues spilling over the Syrian border. This should be another "red line" in Mr Obama's calculation.

Allegations that the regime fired chemical weapons have swirled since December. Initially, the allegations proved false; US officials said in January that the regime misused a riot-control gas. But two reports since March have been more conclusive. One report, from The Times of London, said civilians died twitching, hallucinating and choking on white froth that poured from their noses and mouths, possibly the work of nerve gas. That report buttresses US intelligence reports that the Syrian regime may have used sarin gas on a small scale.

Determining who pulled the trigger with certainty is complicated by the nature of the crisis. We may never know until the war is over. But certainly, access to these materials would be easier for the regime, which is known to possess large stocks. Meanwhile, the regime has been consistently escalating its use of weapons of terror for over two years, from bullets to tanks to mortars to Scud missiles.

And yet, instead of recognising the immense implications of the use of these devices, there has been more focus on whether the scale of their use would qualify as crossed "red line" or a "game changer".

Mr Obama may have boxed himself in with his words, but it is the Syrians on the wrong side of canisters of gas who will suffer most for it. Indeed, every line in Syria has been painted by the colour of blood for far too long.