Isis militants are suspected of firing a shell loaded with a chemical agent during an attack on US and Iraqi troops in northern Iraq, a Pentagon spokesman said.
If confirmed, it would be the first recorded chemical attack on US troops since the Islamic State overran parts of northern and western Iraq in 2014.
According to Navy Captain Jeff Davis, only one of the shells lobbed at Qayyarah Airfield West, where US troops are based, tested positive for a mustard agent. There were no US casualties, Davis said, and the shell, "likely a rocket or mortar, was imprecise and crude".
No service members showed any signs of mustard agent exposure, Davis added. Concentrations of mustard gas can cause agonising burns and blisters, blindness and permanent disfigurement. US troops often deploy with protection against chemical weapons, including gas masks.
Migrant boat capsizes off Egypt
A boat carrying around 600 people capsized off Egypt's coast, killing at least 42, officials said, in the latest disaster to befall migrants attempting to make the crossing to Europe.
The boat sank in the Mediterranean Sea off Burg Rashid, a village in the northern Beheira province. Rescue workers have so far saved 150 people, officials said. The boat was carrying Egyptian, Syrian, and African migrants, they added.
Blaze in Stockholm
Firefighters were battling to contain a blaze at Stockholm's Royal Institute of Art that sent a plume of smoke across Sweden's capital. Dozens of firefighters struggled to contain the blaze, which raced through the attic and roof of the building on Skeppsholmen island near downtown Stockholm. The cause of the fire was not immediately clear and there were no reports of injuries.