Five men from Yemen were freed from the U.S. Navy base at Guantanamo Bay, Cuba, after more than a dozen years of captivity.
Four of the men went to Oman: Al Khadr Abdallah Muhammad Al Yafi, Fadel Hussein Saleh Hentif, Abd Al-Rahman Abdullah Au Shabati, and Mohammed Ahmed Salam.
One, Akhmed Abdul Qadir, was sent to Estonia, according to a Pentagon statement. It was the first time either nation accepted Guantanamo prisoners for resettlement.
The release is the latest in a wave that have alarmed congressional opponents of closing the detention center.
The men had been cleared for release since at least 2009 but the U.S. has balked at repatriating Guantanamo prisoners back to Yemen, where the government is battling an al-Qaeda insurgency.
All five were captured in Pakistan and detained by the U.S. as suspected al-Qaeda fighters. None were ever charged with a crime, the Miami Herald reports.
U.S. officials later determined it was no longer necessary to detain them but have struggled to find other countries willing to take them in.
The men are all in their 30s and 40s, including one who was 17 when he was sent to Guantanamo.