The US is reviewing whether to restore the Iranian-backed Houthis to its list of terrorist organizations after rebels seized a ship Sunday in retaliation for the war in Gaza.

“In light of the recent targeting of civilians by the Houthis, and now the piracy of a ship in international waters, we have begun a review of potential terrorist designations, and we’ll be considering other options together with our allies and partners,” National Security Council spokesman John Kirby told reporters Tuesday. 

Kirby said the seizure of the Galaxy Leader, which is beneficially owned by a unit of Israeli businessman Rami Ungar’s Ray Shipping Group, represented “a flagrant violation of international law” and called Iran’s involvement unacceptable. 

“Iran is complicit to its material support, and its encouragement of the Houthi forces who conducted the seizure — absolutely unacceptable,” he said. 

A spokesperson for the Houthis has said Israeli ships would continue to be targeted until the country’s military operation against Hamas ends. Israel launched a campaign against Hamas — which the US and European Union have designated a terrorist organization — following the militant group’s deadly Oct. 7 attack. 

The Biden administration removed the terrorist designation for the Houthi fighters early in Joe Biden’s presidency as part of a US push to end their war with Yemen’s Saudi-backed government. But the US president has been under pressure to restore the terrorism label, including from some allies in the Middle East and members of Congress. 

Re-designating the Houthis as a Foreign Terrorist Organization “would send a powerful message that the United States views this group as a clear threat to our Allies and partners and to regional stability in the Middle East,” a group of US senators, including North Carolina’s Thom Tillis and Florida’s Marco Rubio, said in a letter to Secretary of State Antony Blinken earlier this month.

Ships have often been caught up in the tension between various groups in the Middle East, at times disrupting the flow of energy and other goods. The Houthis have regularly claimed responsibility for attacks in the Red Sea and the Gulf of Oman.

They have also targeted sites in the United Arab Emirates and Saudi Arabia with drones and missiles — including in 2019 when they briefly knocked out half the kingdom’s oil production.

The Trump administration designated the Houthis as a foreign terrorist organization in January 2021. The Biden administration reclassified the group in February 2021, saying it would help “ensure that relevant U.S. policies do not impede assistance to those already suffering what has been called the world’s worst humanitarian crisis.”