Pat Dollard | Young Americans

And what of those they don’t know and can’t account for yet, or never will be able to account for? How many of them can they, and do they, track?

WASHINGTON (Reuters) - Between 5 and 10 percent of inmates freed from the U.S. military prison at Guantanamo Bay have returned to terrorism since their release, U.S. Defense Secretary Robert Gates said on Thursday.

Gates was briefed on the statistics after a Kuwaiti man released in 2005 from the U.S. prison on Cuba carried out a suicide bomb attack in the northern Iraqi city of Mosul.

“I was told today that the recidivism rate … those who return to the battlefield, is probably somewhere between 5 and 10 percent — maybe 6, 7 percent, something like that,” Gates said.

“We don’t have a lot of specific cases. We’re talking about one, two, three dozen that we have data on,” he told reporters at the Pentagon.

“We do as careful a vetting job as we possibly can before releasing these people,” he said.

The U.S. military said this week that Kuwaiti former detainee Abdullah Saleh al-Ajmi was responsible for a suicide attack in Mosul last month. It said Ajmi had returned to Kuwait after his release and later gone to Iraq via Syria.

The United States has been widely criticized by human rights groups and foreign countries, including U.S. allies, for holding terrorism suspects in the prison at the U.S. naval base at Guantanamo Bay for years without trial.

The Bush administration says the prison is necessary to hold highly dangerous individuals and that it is moving forward with a military commission system to try some of the inmates.

Gates said some of the prisoners could be freed if their governments were prepared to take them back.

“There are a lot of prisoners down there, frankly, that we would be prepared to turn over to their home government,” he said.

“But the home government isn’t prepared to receive them or we don’t have any confidence that, if they still need to be incarcerated, that the home government will keep them incarcerated,” Gates said.

Gates has said that he pushed for the Bush administration to consider closing the prison after he replaced Donald Rumsfeld as Pentagon chief in December 2006. But he has said legal issues have made progress difficult.

Asked on Thursday if he was any closer to closing Guantanamo, Gates replied: “I don’t think so.”

More than 500 inmates have left Guantanamo since the prison opened in January 2002 and some 270 remain, the Pentagon says.