Four senior U.S. intelligence officials say there are “increasing suspicions” the Assad regime has used “small amounts of chemical weapons” during recent fighting.

Their suspicions are shared by British officials who say that “witness accounts and preliminary testing” show that chemical weapons were in fact used. 

There is a theory that Assad may be “using these agents in small amounts to test the West’s intentions and chemical weapons detection capabilities.” 

However, neither this theory nor the opinion that chemical weapons have been used is shared by all. Some, within both the U.S. and Britain, have cast doubt on the conclusions by suggesting the samples that tested positive “may have been tainted by rebels who want to draw the West into the conflict on their side.”

This is a pivotal point, and U.S. entry in the conflict in Syria could be at stake. President Obama has made it clear the use of chemical weapons is a “red line” for the U.S.