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Despite gaining their freedom by signing pledges to renounce violence, at least seven former prisoners of the United States at Guantanamo Bay (search), Cuba, have returned to terrorism, at times with deadly consequences.

At least two are believed to have died in fighting in Afghanistan (search), and a third was recaptured during a raid of a suspected training camp in Afghanistan, said Lt. Cmdr. Flex Plexico, a Pentagon spokesman. Others are at large.

Additional former detainees have expressed a desire to rejoin the fight, be it against U.N. peacekeepers in Afghanistan, Americans in Iraq or Russian soldiers in Chechnya (search).

Some 146 detainees have been released from Guantanamo, but only after U.S. officials had determined the prisoners no longer posed threats and had no remaining intelligence value.

Pentagon officials acknowledged that the release process is imperfect, but they said most of the Guantanamo detainees released have steered clear of Islamic insurgent groups.

The small number returning to the fight demonstrates the delicate balance the United States must strike between minimizing the appearance of holding people unjustly and keeping those who are legitimate long-term threats, Pentagon spokesman Bryan Whitman said.

Human rights groups frequently criticize the Defense Department for holding the hundreds of prisoners at the naval base, largely without charges or legal counsel. Many have been held for more than two years; only a few have been charged.

An additional 57 Guantanamo prisoners have been transferred to the custody of their home governments: 29 to Pakistan; seven to Russia; five each to Morocco and Britain; four each to France and Saudi Arabia; and one each to Spain, Sweden and Denmark, the Pentagon has said.

The Pentagon did not identify the seven detainees believed to have returned to fighting, although a few names have been made public. One released detainee killed a judge leaving a mosque in Afghanistan, Plexico said.

Those in the small group that has gone back to fighting come mainly from the upper echelons of suspected militant or terror groups, some allegedly linked to Al Qaeda, several counterterrorism officials in the Middle East said. They gave no details, but one noted a trend that lower-echelon members tend to get on with their lives after they are released.

The former prisoners include Abdullah Mehsud, a former Guantanamo Bay detainee linked to Al Qaeda who oversaw the recent kidnapping of two Chinese engineers, one of whom was killed.