The Wall Street Journal reports the U.S. transferred five detainees from the prison at Guantanamo Bay—including four men from Yemen, the first Yemeni detainees transferred since 2010, defense officials said Thursday. The U.S. banned transfers of Yemeni detainees to Yemen after Umar Farouk Abdulmutallab , a Nigerian man, attempted to blow up an airliner on Christmas Day 2009 with an underwear bomb made by a Yemen-based terror group. Yemeni detainees are the largest group in Guantanamo, and transferring those detainees from the prison remains an obstacle to closing it, according to human rights advocates. There now are 143 men held at Guantanamo, including 84 Yemen nationals, according to the Pentagon. Of the Yemenis held at the prison, 54 are eligible to be transferred from Guantanamo and have been cleared for release, the Pentagon said.