Acid test

摘要

Barack obama has long said that America would re-gard the use of chemical weap-ons in Syria as crossing a red line: if Bashar Assad deployed them, in other words, the United States would intervene in Syr-I ia's civil war. Now evidence is mounting of such a crime. If it proves solid, Mr Obama's reaction will show Mr Assad, and the rest of the world, whether American threats are to be taken seriously.