US: Shell that hit Iraqi base contained sulfur-mustard agent

The top US general says a rocket that landed on a military base in northern Iraq contained chemical agents that cause human skin to blister.

Marine Gen. Joseph Dunford was asked at a Senate Armed Services Committee hearing today about the disclosure a day earlier that the Islamic State may have attacked the base with chemical weapons.

US officials said today that an oily substance found on a fragment of the rocket initially tested positive for mustard agent, but that a second test was negative. They said further laboratory testing was scheduled.

Dunford said unequivocally that the weapon contained a "sulfur-mustard blister agent" and that no one was injured. He said the Islamic State has a rudimentary capability to deliver chemical weapons. Nonetheless, he called the attack a "concerning development.