US Ambassador to the UN Nikki Haley (R) and British Ambassador to the UN Karen Pierce (L) veto Russian-drafted resolution on investigation by the OPCW into alleged chemical attack in Douma, Syria, at UN HQ, New York, April 10, 2018. Li Muzi/ Press Association. All rights reserved.The chemical-weapons attack on Douma, an area of Damascus beyond the control of Bashar al-Assad's regime, on 7 April has led to high expectation of an imminent military response by the United States, possibly with the involvement of United Kingdom and French forces. Trump's instant assurances of punishment of the "animal" Syrian president fuel the sense that sudden escalation is likely.
The American president's later tweets, early on 12 April, imply a delay in any timetable. But the prospect of dangerous military confrontation remains high. So what, realistically, could happen?
There is a spectrum of offensive options for US and other western militaries. But in broad terms there are three levels of action against the regime:
