Iran seized an oil tanker in the Gulf of Oman on Thursday that was confiscated by the United States just last year.

In September, the U.S. captured the oil tanker along with Iranian oil due to sanctions related to Iran’s nuclear program, according to The Associated Press. Now Iran has retaliated by capturing the same tanker, and the seizure follows months of attacks on shipping by Yemen’s Houthi rebels in the Red Sea.

What’s happening in the Red Sea?
Who are Yemen’s Houthis?

En route to Turkey carrying Iraqi oil, the tanker changed course after six masked soldiers boarded and headed to Iran instead, The Guardian reported.

The seizure followed an order by an Iranian court, according to CNN.

After the September seizure by the U.S., Iran had warned that the action would “not go unanswered,” per Reuters.

Tension in the region has been steady since the Iran-backed Houthis began attacking Red Sea vessels in response to the Hamas-Israeli war.

“The biggest container shipping companies have been forced to divert vessels around Africa, hitting trade and pushing up freight costs,” CNN reported. “Oil executives worry that the Israel-Hamas war may escalate into a regional conflict and disrupt exports of crude.”