US President Donald Trump has claimed that Iranian forces shot down a military helicopter during a patrol over the Strait of Hormuz, prompting him to vow retaliation.
A US uncrewed naval drone boat rescued two crew members from the helicopter after it went down, officials said, and both pilots on board survived.
Trump said the US must respond to the attack, which is the first known loss of an Apache helicopter since the US and Israel's war on Iran began in February.
The incident is the latest flare-up of violence endangering the fragile Iran-US truce, which has repeatedly come under strain due to ongoing clashes across the region.
The US military's Central Command (CENTCOM) is investigating the cause of the incident, and the pilots are in stable condition.
