President Donald Trump has said a US warship has "destroyed" an Iranian drone in the Strait of Hormuz.
He claimed it was the latest "hostile" action by Iran, as tensions between the two nations continue to rise.
He said USS Boxer took "defensive action" against the drone which was "threatening the safety of the ship and the ship's crew".
The drone came within around 1,000 yards of the ship and ignored "multiple calls to stand down", President Trump said.
Speaking at the White House, he said: "This is the latest of many provocative and hostile actions by Iran against vessels operating in international waters.
"The United States reserves the right to defend our personnel, facilities and interests."
Iran's deputy foreign minister said the country had "not lost any drone" and suggested the US may have even downed their own drone by mistake.
The incident comes a month after the US claimed Iran had shot down one of its drones in an "unprovoked attack" over international airspace.
However, Iran argued the drone had violated its airspace.
President Trump warned Iran had made a "very big mistake".
The US has blamed Iran for numerous attacks on oil tankers in the Gulf since May.
Iran has denied all accusations.
Meanwhile, tensions have also been rising between the UK and Iran.
Royal Navy ships have been shadowing British oil tankers in the region after Iran threatened Britain would face "repercussions" for the seizure of an Iranian supertanker by Royal Marines off the coast of Gibraltar.
The UK claimed the ship was carrying crude oil to Syria in breach of EU sanctions - Iran again denied the accusation.
Last week, the Ministry of Defence announced it will send a second warship to the Gulf.