The Pentagon most recently released a report in May showing that one in seven former detainees either returned, or is suspected of returning, to terrorist activity. At least two of them have taken leading roles in Al Qaeda in the Arabian Peninsula, the group that has claimed responsibility for the attempted bombing of a Northwest Airlines flight on Christmas Day.
The Obama administration says it will proceed with caution in transferring any more detainees out of Guantanamo Bay but is determined to shutter the facility.
The following is a partial list, based on the information made public by the Pentagon, of former detainees thought to have returned to the battlefield.
Abu Sufyan al-Azdi al-Shihri. He was repatriated to Saudi Arabia in late 2007 and later emerged as a leadership figure with Al Qaeda in the Arabian Peninsula. He was reported killed in a recent attack on Al Qaeda strongholds in Yemen, claims that have been disputed by family members.
Mazin Salih Musaid al-Alawi al-Awfi. He too was repatriated to Saudi Arabia in 2007 and then emerged as a leadership figure with Al Qaeda in the Arabian Peninsula before turning himself in to Yemeni authorities in February.
Ibrahim bin Shakaran and Mohammed Bin Ahmad Mizouz. These two Moroccans were returned to their home country in 2004, only to be convicted in 2007 for involvement in trying to recruit fellow Moroccans for Al Qaeda in Iraq.
Ibrahim Shafir Sen. He was returned to his home country of Turkey in 2003, and was arrested in the Turkish city of Van in early 2008. He was indicted for being a leader of Al Qaeda cells in Van.
Ravil Shafeyavich Gumarov and Timur Ravilich Ishmurat. These two Russian were returned to their home country in 2004 and were arrested the next year by Russian authorities for involvement in a gas line bombing. They were both convicted in 2006.
Said Mohammed Alim Shah. He was repatriated to his home country of Afghanistan in 2004 and was said to have directed a suicide attack in 2007 that killed 31. He also kidnapped two Chinese engineers in 2004 and claimed responsibility for a hotel bombing in Islamabad. He blew himself up in 2007 to avoid capture.
Mohammed Ismail. He was returned to his home country of Afghanistan in 2004 and was recaptured months later for involvement in an attack on U.S. forces near Kandahar.
Yousef Muhammed Yaaqoub. He was repatriated to Afghanistan in 2003 and quickly joined back with the Taliban as a commander. He reportedly aided a jailbreak in Kandahar and was killed in 2004.
Abdullah Majid al-Naimi. He was repatriated to his home country of Bahrain in 2005 and arrested in 2008. He is known to have associated with Al Qaeda.
Majid Abdullah Lahiq al Joudi. He was returned to his home country of Saudi Arabia in 2007 and is said to have since aided terrorists.
Zahir Shah. He was repatriated to Afghanistan in 2007 and has participated in terrorist training since.
Shah Mohammed. He was returned to Pakistan in 2003 and was later killed fighting U.S. forces in Afghanistan.
Ruslan Anatolivich Odijev. He was repatriated to Russia in 2004. Russian authorities said he was involved in several terrorist attacks including one in 2005 that killed police officers in the Caucasus region. He was killed in battle in 2007.
Sabi Jahn Abdul Ghafour. He was returned to his home country of Afghanistan in 2003 and reportedly became a regional commander for the Taliban. He was killed during fighting with Afghan forces in 2004.
Mohammed Nayim Farouq. He was repatriated to Afghanistan in 2003, and renewed contact with the Taliban and Al Qaeda.
Abdullah Kafkas. He was returned to Russia in 2004. He is suspected of being involved in an attack on a police checkpoint in 2005.
Almasm Rabilavich Sharipov. He was returned to Russia in 2004 and has since associated with the terrorist group Hezb-e-Tahrir.
Abdullah Ghofoor. He was repatriated to Afghanistan in 2004 and became a suspected Taliban commander. After planning attacks on U.S. and Afghan forces, he was killed in a raid.
Saad Madhi Saad Hawash al Azmi. He was returned to Kuwait in 2005 and is suspected of associating with Al Qaeda.
Isa Khan. He was returned to Pakistan in 2004 and later associated with a group called Tehrik-i-Taliban.
Muhibullah. He was repatriated to Afghanistan in 2005 and later associated with the Taliban.
Humud Dakhil Humud Said al-Jadan. He was returned to Saudi Arabia in 2007 and is thought to have associated with known terrorists.
Abd al Razzaq Abdallah Ibrahim al-Sharikh. He was returned to Saudi Arabia in 2007 and was arrested a year later for supporting terrorism.
Abdullah Gulam Rasoul. He was repatriated to Afghanistan in 2007 and is thought to have become a Taliban commander who organized an attack on U.S. aircraft.
Haji Sahib Rohullah Wakil. He was returned to Afghanistan in 2008 and has since associated with terrorist groups.