Iran’s Islamic Revolutionary Guard Corps (IRGC), the theocratic wing of the Iranian military and a designated terrorist organization, seized the South Korean-flagged tanker Hankuk Chemi in the Persian Gulf on Monday.

Iranian media claimed the ship was seized because it was “polluting the Persian Gulf with chemicals.” The South Korean government demanded its immediate release and deployed an “anti-piracy unit” to the Strait of Hormuz.

The ship was surrounded by IRGC speedboats and boarded off the coast of Oman on Monday, then taken to an IRGC naval facility in the Iranian port city of Bandar Abbas. The tanker’s cargo reportedly included 7,200 tons of ethanol. The crew of twenty, including citizens of South Korea, Indonesia, Vietnam, and Myanmar, has been detained by the Iranians.

Iranian state media claimed the Hankuk Chemi was impounded for “polluting the Persian Gulf with chemicals” and sought to minimize the incident as “purely a technical matter.”

Deutsche Welle (DW) reported the ship was traveling from Saudi Arabia to the United Arab Emirates via the Strait of Hormuz, an area of the Persian Gulf that Iran often threatens to blockade or sabotage.

DW pointed out that Iran is currently engaged in a dispute with South Korea over $7 billion in funds frozen by South Korean banks after the United States withdrew from the Iran nuclear deal and reimposed sanctions. Iran also announced Monday that it has begun enriching uranium up to near-weapons-grade levels.

The Jerusalem Post noted the South Korean tanker was seized only a few hours after the Pentagon reversed its decision to bring the aircraft carrier USS Nimitz home from the Persian Gulf, citing the need to counter threats posed by Iran. 

“Iran’s Islamic Revolutionary Guard Corps was already hunting for vessels to harass. They wanted to find a ship to seize, much like they had mined six ships in the Gulf of Oman in May and June 2019, seized a British ship in the summer of 2019, harassed U.S. vessels in the first months of 2020 and apparently mined an Iraqi ship last month,” the Jerusalem Post wrote.

The South Korean Foreign Ministry and its embassy to Iran stated Monday they have “learned that the crews are safe, and are requesting the early release of the ship.”

“The defense ministry said that the country’s anti-piracy Cheonghae Unit is moving toward the scene, and that it will respond in cooperation with the ministries of foreign affairs and fisheries, and a multinational naval force operating in nearby waters,” South Korea’s Yonhap News reported.

An official with the operators of the tanker, DM Shipping, denied the IRGC’s allegations of pollution and told Yonhap the ship’s captain was not told why the Iranian forces were taking control of his ship. The captain transmitted an anti-piracy alarm when the Iranians boarded his vessel.