CAIRO (AP) — Iran-backed rebels fighting in Yemen released three foreign vessels on Wednesday that they seized south of the Red Sea, freeing 16 crew members, South Korea’s Foreign Ministry said.

The vessels — two belonging to South Korea and one to Saudi Arabia — had been captured by Houthi rebels on their way to the Saudi port of Jizan. Two South Korean nationals were among those set free, the ministry said.

The Houthis said they had detained the vessels for entering Yemeni waters earlier this week and routed them to the Red Sea province of Hodeida.

The Saudi-led coalition battling the Houthis in Yemen confirmed the return of the impounded ships. “We are continuing our efforts to maintain maritime security in the Strait of Bab al-Mandeb and the southern Red Sea,” its statement said.

The coalition condemned the seizure of ships in the key oil supply route as a threat to international trade.

The Houthis have frequently targeted oil tankers and military ships belonging to Saudi Arabia and its coalition partners, which have been fighting in Yemen’s civil war since 2015.