U.S. doubts on Syria lie in how sarin exposure occurred

U.S. intelligence agencies unanimously agree that Syrians have been exposed to deadly sarin gas in recent weeks, but they are divided over how certain they can be that the Syrian regime is to blame, U.S. and congressional officials said Friday.

As the Obama administration weighs how to respond to the use of poison gas, intelligence officials say they are confident that sophisticated tests of tissue and soil samples and other evidence point to sarin. But reactions in the U.S. intelligence community have varied because of the possibility — however small — that the exposure was accidental or caused by rebel fighters or others outside the Syrian government’s control, officials said.

Releases of poison gas could have occurred when soldiers loyal to the regime, which has been trying to secure and consolidate its dozens of chemical weapons sites, moved part of its stockpile, a U.S. Defense official said. Another possibility is that disloyal Syrian weapons scientists supplied chemicals to rebel fighters.