| An offensive to retake Mosul from IS is expected in the coming weeks |
A rocket launched by Islamic State
militants at American troops based in Iraq did contain a mustard agent,
the US military has confirmed.
But the attack, he added, was a "concerning development". IS has long been suspected of making and using crude chemical weapons in Iraq and Syria, where it also controls territory.
Gen Dunford told the US Senate armed services committee on Thursday that the rocket had contained a "sulphur-mustard blister agent". Mustard agent in sufficient quantities can maim or kill by damaging skin, eyes and airways.