Kharg, an Iranian Navy training and logistics ship, caught fire in the Gulf of Oman in the early hours of Wednesday local time. After more than 20 hours of firefighting and rescue operations, the ship subsequently sank near the port of Jask. All 400 crew were rescued, with 33 reported injured. The Tasnim news agency, citing a statement from Iran’s navy, said that the ship had been deployed to international waters to participate in a naval exercise when “one of its systems” caught fire. The fire was reported to have started in the ship’s engine room.

Kharg, the largest ship in the Iranian Navy by tonnage, was a converted fleet oiler and had been in service almost 40 years.

The cause of the fire and sinking is the subject of considerable speculation. As reported by the AP, the fire Wednesday … follows a series of mysterious explosions that began in 2019 targeting commercial ships in the Gulf of Oman. The U.S. Navy accused Iran of targeting the ships with limpet mines, timed explosives typically attached by divers to a vessel’s hull.

Iran has denied involvement in the attacks and has also accused Israel of attacks on Iranian ships. In April, an Iranian ship called the MV Saviz believed to be a Revolutionary Guard base and anchored for years in the Red Sea off Yemen was targeted in an attack suspected to have been carried out by Israel.

The NYTimes notes that Iran also has a history of naval disasters that are apparently unrelated to external enemies. During a military training exercise last year, a missile from an Iranian frigate mistakenly struck another ship near the same port, Jask, killing at least 19 sailors and wounding 15. 

Thanks to David Rye for contribuitng to this post.