President Donald Trump talks with reporters before boarding Air Force One at John F. Kennedy International Airport in New York, early Tuesday. AP-Yonhap

WASHINGTON/BEIRUT/DUBAI — U.S. President Donald Trump said on Tuesday Iran had shot down a U.S. Apache helicopter that was patrolling the Strait of Hormuz overnight and vowed to respond, but gave no other details.

"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 wrote in a social media post.

He said the two U.S. pilots involved in the incident were both safe and uninjured.

"Nevertheless, the United States must, of necessity, respond to this attack," he added.