WASHINGTON (AP) — U.S. airstrikes against an al-Qaida-linked militant group in Yemen killed a former detainee at Guantanamo Bay, Cuba, who was released in 2009 despite earlier recommendations that he remain in custody because he was considered a "high threat" to America and its allies.

The Pentagon says Mohammed Tahar, a Yemeni who was held at the detention center for seven years, was killed Thursday.

A March 2008 memo from the detention center commander warned that Tahar "will engage in extremist activities upon release. He has threatened (Guantanamo) personnel and continues to support jihad."

The 12-page memo, signed by Rear Adm. Mark Buzby, who was commander at the detention center at the time, raised Tahar's risk level from medium to high. And it described him as a problem detainee involved in 65 disciplinary incidents, including assaults on the guard force and other disturbances.

It is not clear why Tahar was released in 2009. That year, amid then-President Barack Obama's vows to close Guantanamo, the Defense Department revamped the military commissions involved in the prosecution of the detainees. Some of the changes made statements resulting from torture or degrading treatment inadmissible as evidence in trials and also limited the use of hearsay in the cases.

In 2010, the U.S. stopped releasing Yemeni detainees because most countries were unwilling to take them, and it was difficult to ensure they would not return to the battlefield. The U.S. won't send Yemeni prisoners to their homeland because it is too unstable, so other countries must be found to take them.

It was four years before any Yemenis were transferred out of Guantanamo again. Even now, a number of the roughly 55 detainees who remain at Guantanamo are Yemeni, including some who have been cleared for release. Four were released in January, and were sent to Saudi Arabia.

Also killed in the Yemen airstrike was Usayd al-Adani, an explosives expert and district leader of the group, al-Qaida in the Arabian Peninsula.

Navy Capt. Jeff Davis said the latest strikes in Yemen's Abyan region bring the total number of attacks to more than 40 over the past five days.