US President Donald Trump has accused Iran of shooting down a US Apache helicopter that was patrolling the Strait of Hormuz and has vowed to respond.Two crew members aboard the US Army Apache attack helicopter were rescued by a US sea drone after the aircraft crashed near the Strait of Hormuz on Tuesday morning, local time."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," Mr Trump wrote in a social media post."Nevertheless, the United States must, of necessity, respond to this attack."Mr Trump said both crew members were uninjured in the crash.A drone boat rescued the crew that crashed off the coast of Oman, according to Captain Tim Hawkins, a spokesperson for US Central Command.He said the unmanned boat found the two aviators, who had spent about two hours in the water, and brought them to shore.It was the first known drone rescue at sea by the US military, he said.Iranian Foreign Minister Abbas Araghchi did not directly address the incident, but said foreign forces in the region risked being involved in accidents or crossfire."To reduce risk, best solution is for them to leave," he said on social media.Moments before Mr Trump said the US "must" respond, Iran's parliamentary speaker, Mohammad Baqer Qalibaf, warned the US against risking an escalation."We prefer the language of diplomacy, but we speak other languages far more fluently," he wrote on X."Break your commitments, and we'll switch to what we speak best You ride the horse you saddled!"The Apache helicopter is the second crewed aircraft Washington has confirmed as being shot down by Iran during the war