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Once these 17 are released, the number of those eligible for transfer would drop from 48 to 31

During Barack Obama's presidency, the number of detainees has dwindled from 241 to 107

Washington CNN  — 

Secretary of Defense Ashton Carter has approved the transfer of 17 more detainees held in Guantanamo Bay as the Obama administration attempts to whittle down the population at the facility, a U.S. defense official told CNN on Thursday.

The official said the 17 won’t be released right away because they are still within a 30-day time period during which Congress is notified. Once these 17 are released, the number of those eligible for transfer would drop from 48 to 31, while the facility’s total population would drop to 90.

The official said the destination countries for the 17 detainees have already been determined, but would not disclose them until after the transfers took place.

President Barack Obama says the prison – which holds suspected members of terrorist groups captured overseas – is a recruiting tool for terrorists and is too costly to maintain. During his presidency, the number of detainees has dwindled from 241 to 107, and he said last month he expected that number to get below 100 by early next year. But he has hit roadblock after roadblock – most often placed by Capitol Hill – in his effort to clear out the prison.

In 2009, an effort to transfer 17 Uighur detainees – members of a Chinese Muslim minority deemed no threat to the United States – to northern Virginia collapsed after the region’s lawmakers revolted.

In May of that year, the Democrat-controlled Senate voted overwhelmingly against allowing government funds to close Guantanamo. An administration plan to move detainees to a supermax prison 150 miles south of Chicago met a similar fate in Congress.

In balking at the transfers, Republican and Democrat lawmakers alike repeatedly cited security fears expressed by their constituents about housing suspected terrorists near their families.

Legislators later banned the administration from transferring any detainees into the United States in a war spending bill that Obama aides deemed too important to veto.