Humanitarian worker Sandra Loli and businessman Mikael Gidada who were held by hostage by Houthi militants in Yemen have been freed as part of a U.S.-backed prisoner exchange with Saudi Arabia. According to the Wall Street Journal (via American Military News), the two Americans, along with the remains of a third American, Bilal Fateen, who died while imprisoned, were turned over by Houthi militants in exchange for the release of more than 200 captured Houthi militants held by the Saudis.

The Saudis weren’t too keen to release their prisoners.

One Saudi official told the Wall Street Journal that the prisoner exchange was “very difficult for Saudi Arabia because the Houthis are continuing to target the kingdom’s lands with Iranian-made missiles and drones, and they reject the U.N. envoy’s proposals. We need to find a balance between Saudi efforts in Yemen to achieve peace and to support our allies in America in releasing the Americans. We need to support peace from different angles.”

Kash Patel, a deputy assistant to President Trump who worked on the prisoner exchange said the U.S. vetted the Houthi militants being released in the exchange to ensure none were on any American terrorism lists and blocked the return of some militants who they did deem to be too high-risk for release.

Patel told the Wall Street Journal “We had teams on the ground in both locations [Yemen and Oman] to ensure that there was a proper screening conducted of the people going back and that the cargo manifest was inspected so we could ensure the Saudis that no lethal aid was being provided and no known terrorist was being sent back.”

Fingers crossed.

Most of the Houthi militants freed in Wednesday’s exchange had been flown to Oman several years ago for medical care as part of a U.N.-brokered goodwill gesture from the Saudi-led coalition to the Houthis.

The parties hoped the gesture would help kick start peace talks, but once the Houthis arrived in Oman, the Saudis blocked their return to Yemen.

Saudi Arabia is worried the released prisoners could potentially return to the battlefield in the ongoing conflict between the Iran-backed Houthis and the Saudi-led military coalition in Yemen. The Saudis said dozens of the released Houthi militants were trained to operate advanced drones and missiles.

Yemen has been in the midst of a bloody civil war for the last five years. In January 2015, Houthi rebels – Shiite Muslims backed by Iran – seized control of the much of the country including the capital Sanaa and forced the president to flee the country.

A coalition led by Saudi Arabia and other Sunni-majority nations have been supporting government forces in the war.

Armed with state-of-the-art US and British warplanes, Saudi Arabia’s air force and its allies have complete air superiority in the skies over Yemen, but have been criticized for the high civilian death counts after air strikes.

The civil war has a been a tragedy of epic proportion, claiming as many as100,000 lives as a result of direct involvement and the knock-on effects of mass starvation and inadequate sanitation in the desperately poor country.

Charity UNICEF says approximately 80 percent of Yemen’s population, or 24 million people, rely on aid, and 10 million are facing famine.

National Security Adviser Robert O’Brien thanked Saudi Arabia and Oman for backing the negotiations that allowed for the release of the American hostages. U.S. officials said they had worked urgently on the deal to secure the two captive Americans as Loli’s health was in decline.