The Foreign Secretary William Hague told MPs the Ministry of Defence has been preparing contingency plans to deal with the "heightened" understanding of the threat of chemical weapons being used by Assad's regime in Syria. Mr Hague said:
Our understanding of this threat has been heightened in recent days, we have seen some of the same evidence as the United States.
We have expressed in no uncertain terms directly to the Syrian regime the gravity of any use of chemical weapons. In our view, as the Prime Minister has said before, this would require us to revisit our approach on Syria.
I can't discuss contingency plans in any detail but we are always, in the UK, including in the Ministry of Defence, ready with a wide range of contingency plans.
General Richard Myers has told ITV News that the real threat in Syria is from Islamist groups using chemical weapons - not President Assad.
NATO agrees to deploys Patriot missiles along the Syria/Turkey border but denies claims that it is taking an active role in the conflict.