President Donald Trump said Tuesday the Iranians shot down the U.S. Apache helicopter that fell overnight near the Strait of Hormuz and is calling for a response. 

“I have just been informed by our Great Military that last night the Iranians shot down one of our highly sophisticated Apache Helicopters while patrolling over the Strait of Hormuz,” Trump said in a post on Truth Social. 

Earlier Tuesday there had been some uncertainty about whether mechanical problems caused the crash or an attack. Both pilots of the aircraft, Trump said, were rescued and unharmed, but he said that the U.S. must “of necessity” respond to the attack. 

This is the first Apache helicopter known to be lost in the conflict with Iran.