"American Forces are maintaining their defensive posture & that has not changed," the chief Pentagon spokesperson said.

U.S. refueling aircraft and warships have been dispatched to safeguard U.S. interests as the deadly conflict shows no sign of abating.

Bazan Group, operator of Israel's largest refinery complex in Haifa, said it had shut down operations after a power plant supplying steam and electricity to the complex was damaged in a barrage from Iran.