Fragile US-Iran ceasefire tested as drone strike off Oman draws stern warning from the US president.

United States President Donald Trump has condemned what he called Iran’s “foolish violation” of the ceasefire agreement after a drone struck a cargo vessel in the Strait of Hormuz.

Trump did not identify the ship in his post on Truth Social on Friday. But the British military said that a vessel was hit by a projectile off Oman on Thursday.

The Singapore-flagged Ever Lovely, owned by Taiwan-based Evergreen Marine – had been stranded in the Gulf for more than 100 days after loading cargo in Iraq.

No crew members were injured and the ship was able to continue its voyage. US forces intercepted three other drones launched in the same coordinated attack.

“One of the Drones solidly hit the upper deck of a large and very expensive Cargo Carrying Ship. Damage was done, but the Ship was able to proceed on its way,” Trump wrote.

“Obviously, this is a foolish violation of our Ceasefire Agreement,” he added.

Iran has not claimed responsibility for the attack, but two US officials told the Reuters news agency on condition of anonymity on Thursday that Iran fired on the ship.

It comes at a fragile time, as the US and Iran are negotiating an interim peace deal.

They are in the midst of a 60-day memorandum of understanding recently signed between Washington and Tehran, with both sides agreeing to lift naval blockades and open the Strait of Hormuz to free passage while negotiators work towards a longer-term deal on Iran’s nuclear programme and sanctions relief.

The Ever Lovely had chosen a southern route along the Omani coast rather than corridors designated by Iran’s Islamic Revolutionary Guard Corps (IRGC), which hours before the attack had issued a directive demanding all commercial vessels coordinate directly with the Iranian Navy.

The attack immediately halted International Maritime Organization (IMO) efforts to escort hundreds of stranded vessels out of the Gulf, where more than 11,000 seafarers have been trapped for months.

Iran earlier expressed anger at what it said was an “interventionist, irresponsible and provocative” statement by the US and six Gulf ⁠states that rejected its assertion that it could charge tolls on vessels transiting the strait.

Iran’s Deputy Foreign Minister, Kazem Gharibabadi, defended Tehran’s position on Friday, writing on X that “safe passage through the Strait of Hormuz cannot be guaranteed under ambiguous arrangements, parallel routes or decision-making that does not take Iran’s role as a coastal state into account.”

The IRGC denied US assertions that a direct communication line had been established between Tehran and Washington regarding the strait.

“This is a complete lie and we strongly deny it,” IRGC spokesperson Brigadier General Hossein Mohebbi said in a statement cited by Iran’s official news agency IRNA. “The Strait of Hormuz is Iranian territory and has no connection to the United States,” he added.

Al Jazeera correspondent Mike Hanna, reporting from Washington on Friday, said that Trump’s social media post came several hours after the attack, instead of immediately after, as most of his responses to current events typically appear.

“It’s also, by Trump’s terms, a somewhat subdued message,” Hanna said about the Truth Social post. “Normally, there is much more anger involved. But it is at the same time a pretty strong warning from the president about the dangers of violating the ceasefire agreement.”