The US military shot down an Iranian drone on Thursday that came within 1,000 yards of one of its naval vessels in the Strait of Hormuz, President Donald Trump said.
The USS Boxer "took defensive action" against the Iranian drone as it was "threatening the safety of the ship and the ship's crew," Trump announced at the White House.
"The drone was immediately destroyed," he added.
The downing of the drone comes at a time of mounting tensions in the Gulf region between the US and Iran which has been slapped with a raft of sanctions by the Trump administration.
"This is the latest of many provocative and hostile actions by Iran, against vessels operating in international waters," said Trump.
"The United States reserves the right to defend our personnel facilities, and interests and calls upon all nations to condemn Iran's freedom of navigation and global commerce.
"I also call on other nations to protect their ships as they go through the Strait and to work with us in the future."