TEHRAN, April 20, 2026 (BSS/AFP) - Iran's military has vowed to respond after a US destroyer on Sunday fired on an Iranian-flagged cargo ship in the Gulf of Oman that tried to evade a US naval blockade.

"We warn that the armed forces of the Islamic Republic of Iran will soon respond and retaliate against this armed piracy and the US military," said a spokesperson for the military's central command centre, Khatam Al-Anbiya, cited by ISNA news agency.

He accused the United States of having "violated the ceasefire" that has been in place since April 8.

US President Donald Trump posted Sunday on Truth Social that after the Iranian vessel, Touska, ignored warnings to stop, the guided missile destroyer USS Spruance "stopped them right in their tracks by blowing a hole in the engineroom".

"Right now, U.S. Marines have custody of the vessel," the US president added, "and are seeing what's on board!"

The incident comes with tensions high in the Strait of Hormuz, a vital conduit for the world's oil and liquefied natural gas, which has been virtually closed since the start of the US-Israeli war with Iran seven weeks ago.

Iran briefly reopened the strait on Friday in recognition of an Israel-Hezbollah ceasefire in Lebanon, but closed it again the following day in response to the United States maintaining its blockade on ships travelling to and from Iranian ports.

In an earlier post on Sunday, Trump accused Tehran of violating the ceasefire, which expires Wednesday, by launching attacks on Saturday in the vital shipping lane.