Donald Trump has instructed the US Navy to 'shoot down' any Iranian gunboats that 'harass' American ships.
Last week, 11 vessels from Iran's Islamic Revolutionary Guard Corps Navy (IRGCN) came dangerously close to U.S. ships in the Gulf.
The US President tweeted on Wednesday: "I have instructed the United States Navy to shoot down and destroy any and all Iranian gunboats if they harass our ships at sea."
His comments come on the same day Iran's Revolutionary Guards Corps said it had successfully launched the country's first military satellite into orbit, at a time of heightened tensions with the United States over Tehran's nuclear and missile programmes.
U.S. officials have said they fear long-range ballistic technology used to put satellites into orbit could also be used to launch nuclear warheads.
Tehran denies U.S. assertions that such activity is a cover for ballistic missile development and says it has never pursued the development of nuclear weapons.
"Iran's first military satellite, Noor, was launched this morning from the central desert of Iran. The launch was successful and the satellite reached orbit," state TV said.
Close interactions with Iranian military vessels were not uncommon in 2016 and 2017.
On several occasions, U.S. Navy ships fired warning shots at Iranian vessels when they got too close.
While the Navy has the authority to act in self-defense, Trump's comments appeared to go further and are likely to stoke tensions between Iran and the United States.
Earlier this month, the U.S. military said eleven vessels from the IRGCN came dangerously close to U.S. Navy and Coast Guard ships in the Gulf, calling the moves "dangerous and provocative."
At one point, the Iranian vessels came within 10 yards of the U.S. Coast Guard cutter Maui.
While such interactions at sea had occurred occasionally a few years ago, they had stopped recently.
Tensions between Iran and the United States increased earlier this year after the United States killed Qassem Soleimani, the head of Iran's elite Quds Force, in a drone strike in Iraq.
Iran retaliated on Jan. 8 with a rocket attack on Iraq's Ain al-Asad base where U.S. forces were stationed. No U.S. troops were killed or faced immediate bodily injury, but more than 100 were later diagnosed with traumatic brain injury.
