Iran seized a South Korean-flagged oil tanker in the Strait of Hormuz hours before announcing it would increase its nuclear activities, as tensions in the region mount in the final days of Donald Trump’s U.S. presidency.

The Islamic Revolutionary Guard Corps said it detained the Hankuk Chemi vessel at 10 a.m. local time Monday “due to repeated violations of marine environmental laws.”

It’s the latest in a series of shipping incidents in the Persian Gulf, where several vessels have been attacked or seized in recent years.

The events have unfolded against a broader backdrop of rising anxiety in the Middle East as the Trump administration extended its offensive to weaken Iran and force it into deeper nuclear and military concessions.

Concerns of further conflict have grown in the final weeks before Joe Biden takes over in Washington, especially around the recent assassination of a top Iranian nuclear scientist and this week’s first anniversary of the killing of the country’s leading general.

“In the short run, these tactics run the risk of turning into a just cause for war in the waning days of the Trump administration, and in the longer run can poison the well with Biden’s team,” said Ali Vaez, director of the Iran Project at the International Crisis Group.

Iran’s army also announced large-scale drone exercises starting Tuesday following a weekend of defiant speeches accusing the U.S. of aggression.

Korea Reacts

Iran’s announcement Monday that it would start processing uranium to 20% purity marks a further breach of a nuclear deal that Trump, who leaves office Jan. 20, abandoned in 2018.

That announcement came shortly after Washington decided to keep the USS Nimitz in the Persian Gulf because of “recent threats” from Iran’s leaders against Trump. The aircraft carrier had been set to leave the region.South Korea’s Defense Ministry said it ordered the deployment of its naval destroyer ROKS Choi Young to waters near the Strait of Hormuz on Monday.

The Hankuk Chemi’s owner, DM Shipping Co., denied it had broken any marine environmental rules, adding that the vessel was still being held off Iran, according to an official from the company who asked not to be named due to internal policy.

The ship was headed to Fujairah after loading petrochemicals including methane from Jubail in Saudi Arabia and was sailing through the Strait of Hormuz when it was intercepted, the official said. A total of 20 crew members from South Korea, Myanmar, Indonesia and Vietnam were on board the vessel.

The guard corps took the ship to Bandar Abbas port in Iran, the semi-official Fars News Agency said. Iran’s Foreign Ministry later appeared to play down the incident, saying the seizure was related to a “technical issue” and stressed that it’s nuclear move was easily reversible.

Deputy Foreign Minister Abbas Araghchi said that nuclear weapons had “no place” in the country’s defense program, according to Tasnim.

Strained Relations

Relations between Tehran and Seoul have been strained since the U.S. reimposed tough sanctions on Iran and banned countries, including major Asian customers, from buying its petroleum.

Iran says it has at least $7 billion from oil sales trapped in South Korea and the money is needed to purchase humanitarian goods, including coronavirus vaccines. Seoul’s deputy foreign minister was scheduled to visit Iran to discuss the trapped funds, a spokesman for Iran’s Foreign Ministry said just before the tanker was seized.

South Korea is not a member of the International Maritime Security Construct, a maritime force created in 2019 in response to Iranian attacks and to protect sea lanes in the Middle East. Seoul has previously indicated a willingness to work with IMSC, though it has not requested assistance from the alliance so far, said an IMSC spokesman.

The Hankuk Chemi was sailing to the United Arab Emirates port of Fujairah after loading at Jubail on Jan. 2, according to ship-tracking data compiled by Bloomberg. It veered off course in the Strait of Hormuz, a narrow stretch of water between the tip of Oman and Iran, and headed toward Bandar Abbas.

U.K. Maritime Trade Operations, which serves as a link between the Royal Navy and commercial vessels operating in high-risk areas, said there had been “an interaction” between a merchant vessel and the Iranian authorities in the Strait of Hormuz between 6:15 a.m. and 7:33 a.m. London time.

The U.S. Fifth Fleet, which is based in the region, is “monitoring the situation,” spokeswoman Commander Rebecca Rebarich said.

On Dec. 31, a mine was discovered attached to the hull of an oil tanker off Iraq, near the Iranian border. A ship at the Saudi Red Sea port of Jeddah was hit by an explosion earlier in the month, which Riyadh labeled an act of terror.

Iran detained the U.K.-flagged tanker Stena Impero for more than two months at Bandar Abbas in mid-2019 in retaliation for the arrest of one of its ships off Gibraltar. The Islamic Republic seized another oil vessel that was sailing through the Strait of Hormuz around the same time.