President Bush established the detention center at the U.S. naval base at Guantanamo Bay, Cuba, to house detainees from the war in Afghanistan and later Iraq. In 2008, President Obama promised that, if elected, he was shuttin’ it down — it became one of the signature platforms of his whole campaign.
Just after entering office, Obama signed an executive order directing that Gitmo be closed, and that the detainees be reviewed on a case-by-case basis with the goal of repatriating them or bringing them to trial in U.S. civilian courts. Nothing doing, however — Congress blocked his attempt, citing security risks with terrorists attacks and escapes in transferring the criminals. (Being president is hard.)