Saudi Arabia said Thursday it had rescued two young American women from Yemen in a joint special operations mission with the United States.

The Saudi defense ministry said the women, both Yemeni-American teenagers, were being held by Iran-backed Houthi rebels in the Yemeni capital of Sanaa after having been taken captive while visiting their grandmother.

The women were taken by Saudi operatives from Sanaa to Aden, then flown to Saudi Arabia for medical treatment. They have now been repatriated to the U.S., the Saudis said. There was no immediate comment from Washington.

The Saudis did not say when the rescue mission took place but a person familiar with the operation said it occurred in January and was being made public now because the women are now back in the U.S.

“During a family visit to Sanaa, the two U.S. citizens were mistreated by the Houthi militia,” said Saudi Defense Ministry spokesperson Brig. Gen. Turki Al-Malki. “The Houthis also placed restrictions on their freedom and movement, and their passports were confiscated.”

“Following a request from the U.S. and through a special security operation, the two U.S. citizens were freed and then transported from Sanaa to Aden,” he said. “Subsequently, they were flown from Aden to Riyadh by the Royal Saudi Airforce.”

The statement said the joint operation was indicative of cooperation between Washington and Riyadh, something which many have called into question recently due to differences on issues ranging from global oil supplies to Russia’s invasion of Ukraine to the Iran nuclear deal.