A United States Navy destroyer fired warning shots at four fast-attack Iranian patrol boats closing in on the vessel near the Strait of Hormuz, American defence officials said on Monday.
The incident came as President-elect Donald Trump – who last year called for Iranian vessels that harass the US Navy in the Gulf to be “shot out of the water”- pledged to lead the biggest US Navy build-up since the Cold War.
Two defence sources told Reuters that the USS Mahan, a guided-missile destroyer, fired three warning shots at the Iranian fleet after at least one vessel travelled within 800 metres of the ship.
The USS Mahan established radio communication with the Islamic Revolutionary Guard Corps boats but they did not respond to requests to slow down, they said.
A US navy helicopter reportedly dropped a smoke float, and the destroyer tried to stave off the approaching vessels by firing warning flares, before eventually firing the warning shots.
The officials added that the incident was just one of seven interactions the Mahan had with Iranian vessels over the weekend, but the others were judged to be non-threatening.
The standoff came a day before Iran’s parliament voted on Monday to expand the country’s military spending, including funds for a its long-range missile program.
World powers, including Britain and the US, have said the missile programme is “inconsistent” with the 2015 nuclear accord. And Mr Trump has pledged to oppose any expansion of the capability.
The US Navy has released a proposal for a shipbuilding boom following Mr Trump’s campaign pledge to dramatically expand America’s battle force at sea.
The Navy is pitching to expand the US fleet to 355 ships – five more even than the president-elect proposed on the campaign trail, and a large increase from the current 272 – in a project estimated by analysts to cost up to $5 billion (£4.12 billion) a year in a 30-year projection.
Mr Trump’s plan, if enacted, would invest heavily in new submarines and large surface warships intended to act as a deterrent from a resurgent Russia and the growing powerhouse of China.
Mr Trump promised Americans during the election to make our military “so big, so powerful, so strong, that nobody — absolutely nobody — is gonna mess with us”.
Matthew Paxton, president of the Shipbuilders Council of America, which represents most of the major Navy shipbuilders said: “Russia and China are going to continue to build up their navies. The complexities aren’t going to get any easier. The Navy, more than any of the services, is our forward presence. We’re going to need this Navy.”
Many defense analysts agree that military capabilities have been degraded in recent years, especially when it comes to warships, aircraft and tanks.
The expansion would also form part of Mr Trump’s agenda to create jobs, creating thousands of new careers for sailors and revitalising shipyards that have laboured under budget cuts.
At Maine’s Bath Iron Works, workers worried about the future want to build more ships but wonder where the billions of dollars will come from.
“Whether Congress and the government can actually fund it, is a whole other ball game,” said Rich Nolan, president of the shipyard’s largest union.