WASHINGTON — The Obama administration on Sunday announced that it had transferred a Yemeni detainee to Italy. The United States military had held the man in indefinite wartime detention without trial at Guantánamo Bay, Cuba, for 14 and a half years.

The transfer of the prisoner, Fayiz Ahmad Yahia Suleiman, reduced the detainee population to no more than 78. The move comes at a time of heightened scrutiny on detainee releases because of the disappearance of a former prisoner who had been resettled in Uruguay, which Republicans have cited in expressing opposition to further transfers.

The transfer on Sunday showed that the Obama administration, which will most likely be thwarted by Congress in its efforts to close the prison before President Obama leaves office, continues to pursue a lesser goal of getting out every detainee on a list of men recommended for transfer if security conditions are met in receiving countries.

Mr. Suleiman’s departure leaves no more than 29 detainees on the list of those awaiting transfers.

He was among the earliest detainees taken by the George W. Bush administration to the wartime prison when it opened in January 2002. According to a leaked military dossier, he was arrested near the Afghan border by the Pakistani police in late 2001 and was turned over to the American military.