Since a Pentagon official reported two months ago that some dozen former Guantánamo detainees were responsible for the deaths of Americans overseas, the Obama administration has not been forthcoming on the locations or names of those involved.

The disclosure was first made in March by senior Pentagon official Paul Lewis, who oversees Guantánamo issues at the Defense Department, before Congressional lawmakers. Since then, the Obama administration and Lewis have failed to provide further details on the specifics of those attacks or the names of those allegedly involved.

The Washington Post, however, learned from current and former US officials that all of the detainees that were implicated in the attacks were released during the Bush administration. They also discovered that most of the incidents were directed at military personnel, with the dead including one American civilian, a female aid worker who died in Afghanistan in 2008.

Another official told the Post that nine of the detainees are “now dead or in foreign government custody.” “Because many of these incidents were large-scale firefights in a war zone, we cannot always distinguish whether Americans were killed by the former detainees or by others in the same fight,” the official told the Post.

The accusation comes at a politically sensitive time for the Obama administration, which is ostensibly trying to fulfill a 2008 campaign pledge to close the Guantanamo Bay military prison by transferring many of the detainees to third-party countries. Those that are still considered the greatest threat to the US would be transferred to a US location under Obama’s plan. Obama has argued that keeping detainees at Guantánamo only supports terrorist efforts in recruiting soldiers. Just under 700 detainees have been released from Guantánamo since the prison opened in 2002, while 80 inmates remain.

The transfer of detainees to the US mainland has been viscerally opposed by many in Congress as well as state governors who think the plan is misguided and dangerous. Many feel that where the men who are eventually relocated will automatically make the state a target for a future terrorist attack.

In February, the White House submitted a comprehensive plan outlining steps to safely close the detention facility by the end of his presidency. A Senate defense appropriations bill seeks to keep the Guantanamo Bay detention camp running, a plan the Obama administration has threatened to veto over the bill’s ‘troubling provisions.’ “If the president were presented with S. 2943, his senior advisors would recommend he veto the bill,” the administration said in a statement on Tuesday.

The White House expressed opposition to “many provisions” listed in the Senate’s $602 billion National Defense Authorization Act (NDAA) for the next fiscal year, because it would “hinder” the Pentagon’s ability, the president’s own defense strategy and the administration’s ability to carry out national security and foreign policy. “These provisions have nothing to do with the national security of our country, and decrease the economy and efficiency of the federal procurement system,” the statement said.

First and foremost, the White House referred to the bill’s provisions relating to Guantánamo. “Rather than taking the steps necessary to close the facility, this bill includes several provisions that would seek to extend its operation,” the statement said.