Tests Confirm Sarin Gas in Baghdad Bomb. (Hat tip: Occasional Reader.)

WASHINGTON - Comprehensive testing has confirmed the presence of the chemical weapon sarin in the remains of a roadside bomb discovered this month in Baghdad, a defense official said Tuesday.

The determination, made by a laboratory in the United States that the official would not identify, verifies what earlier, less-thorough field tests had found: the bomb was made from an artillery shell designed to disperse the deadly nerve agent on the battlefield.

The origin of the shell remains unclear, and finding that out is a priority for the U.S. military, the defense official said, speaking on the condition of anonymity.

Some analysts worry the 155-millimeter artillery shell, found rigged as a bomb on May 15, may be part of a larger stockpile of Iraqi chemical weapons that insurgents can now use. But no more have turned up, and several military officials have said the shell may have been an older one that predated the 1991 Gulf War.

It likewise is not known whether the bombers knew they had a chemical weapon. Military officials have said the shell bore no labels to indicate it was anything except a normal explosive shell, the type used to make scores of roadside bombs in Iraq.