Shell that hit Iraqi base contained sulfur-mustard agent

Mr Abadi has called on residents to stand up to the group ahead of the military offensive. Mosul is now the largest city still under its control.

Almost 5,000 USA troops are now on the ground in Iraq and “hundreds” of those forces are located at the base, the official said.

However, another officials said: “I don’t know of a case like this where it was proximate to USA forces like this before”.

The Islamic State is believed to have fired a shell containing mustard gas toward the Qayyara Military Base in Iraq Tuesday, where USA and Iraqi forces are operating, according to a report.

The town’s proximity to Iraqi supply lines reaching Qayyara airbase further north, which will be used as a logistics hub for the push on Mosul, lends it strategic importance.

“Oil trenches, tunnels and suicide attacks will not save Daesh from defeat but they will make the battle more challenging”, Sabah al-Numani, a spokesman for the counter-terrorism forces leading the offensive, told Reuters. “We do have some breaking news coming into CNN at this minute”, announced a concerned Jake Tapper, “US officials are telling CNN that the Pentagon suspects ISIS launched a chemical weapons attack against US and Iraqi troops”. Residents inside the city said that in the step up in arrests, several people with Iraqi army ties or family members had been targeted amid Isis fears the population will rise up as coalition forces advance.

The fight for Mosul-seen as the biggest battle yet against Islamic State-has been delayed for more than a year.

The official said a small group of U.S. soldiers who inspected remnants of the rocket after it exploded found a black, oily substance on a fragment of metal. He added that “potentially” the rocket round was “within hundreds of yards” of the USA forces and “within the security perimeter” of the base. They saw something suspicious. That decision would help to focus the so-called YPG, which may be the primary force behind the retaking of the Islamic State stronghold of Raqqa, the de facto capital of the militant group’s caliphate.