WASHINGTON » In a series of secret nighttime flights in the last two months, the Obama administration made more progress toward the president’s goal of emptying the military prison at Guantanamo Bay, Cuba, than it had since 2009. The accelerated pace came after an era of political infighting and long bureaucratic delays.

Now 127 prisoners remain at Guantanamo, down from 680 in 2003, and the Pentagon is ready to release two more groups of prisoners in the next two weeks; officials will not provide a specific number. President Barack Obama’s goal in the last two years of his presidency is to deplete the Guantanamo prison to the point where it houses 60 to 80 people and keeping it open no longer makes economic sense.

Although Obama still has a long way to go, senior administration officials say the president is expecting Ashton B. Carter, his nominee for defense secretary, to move more aggressively on emptying Guantanamo than did Chuck Hagel, the previous defense chief.

Obama may be commander in chief, but Hagel had the power to delay approval of prisoner transfers from Guantanamo for months. Fearful that the freed detainees could become a security threat to U.S. troops abroad, Hagel moved slowly, frustrating the White House, and ultimately resigned under pressure.

Carter’s views on Guantanamo are not widely known, but his colleagues say he is attuned to Washington politics and Obama’s desire to be part of the last chapter of the Guantanamo prison, which the United States opened in 2002 to house people suspected of being connected to terrorist groups.

"If the president doesn’t succeed in making substantial steps to closing Gitmo now, it will have a very severe impact on his legacy," said J. Wells Dixon, senior staff attorney with the Center for Constitutional Rights, which has represented Guantanamo prisoners.

He and other critics of the prison say that Obama must take some of the blame for the failure to close it. After running into resistance in 2009 as he tried to make good on a campaign promise, Obama largely abandoned the effort to shut the prison until 2013, when he announced a revitalized effort. There are 59 remaining low-level prisoners deemed eligible for release, many of them Taliban foot soldiers who were never charged with a crime.

Administration officials say they hope to keep up the current pace, although they acknowledge that after the planned two groups of transfers, the releases may slow down. Officials at the Pentagon and the State Department must negotiate with foreign countries to accept the remaining prisoners that the administration has said should be released.

"I can tell you that in the world of Gitmo transfers and our conversations with foreign governments, momentum matters," said Ian Moss, the State Department spokesman for Guantanamo issues. "We are aggressively reaching out to a wide variety of countries. The support of our friends and allies is critical to achieving our goal of reducing the detainee population and ultimately closing the detention facility."

Paul Lewis, the Pentagon’s special envoy for Guantanamo detention closure, said in an email that "the Defense Department continues to aggressively pursue the transfer" of low-level detainees who have been declared eligible. He added that "we take our obligation to assess the potential threat of detainees seriously prior to transfers," but also said that in 2015 there could be "an increase of detainees eligible to transfer."

In one example of the administration’s eagerness to speed the releases, the White House is no longer waiting for security improvements in Yemen before sending Yemeni prisoners there. A majority of prisoners now at Guantanamo are from Yemen, in large part because both the Obama and the Bush administrations were reluctant to repatriate Yemenis into the chaos there. Both administrations feared that returning Yemeni prisoners could exacerbate a tense situation, and so as large numbers of low-level detainees from other countries were sent home years ago, most of the Yemenis remained.

Both administrations held out hope that matters would improve enough that low-level prisoners from Yemen could be repatriated, and the Obama administration went so far as to repatriate two in 2009. But after al-Qaida in the Arabian Peninsula, which operates in Yemen, tried to blow up a Northwest Airlines flight to Detroit from Amsterdam on Christmas Day that year, Obama imposed an indefinite moratorium on returning prisoners to Yemen.

In 2013, seeking to jump-start his efforts close the prison after detainees went on a widespread hunger strike, he lifted the moratorium. Security conditions in Yemen seemed to improve under the country’s new president, Abdu Rabbu Mansour Hadi, who appeared more eager about taking on al-Qaida.

But since then, Yemen has become more chaotic, and the Obama administration has struggled to bolster Hadi, who was badly undercut when Houthi rebels — who are also fighting al-Qaida — seized control of Yemen’s capital in September.

Congress has security restrictions on the transfer of Guantanamo Bay detainees, and the trouble in Yemen made it difficult for the administration to argue that Hadi’s government could adequately monitor detainees who were repatriated. The Obama administration decided to skirt the issue by transferring Yemenis to other countries.

In November, the Pentagon sent Hussein Salem Mohammed, a Yemeni detainee, to Slovakia, and three Yemenis — Slah Muhamed Salih al-Zabe, Abdul Khaled Ahmed Sahleh al-Bedani and Abdel Ghalib Ahmad Hakim — to the Republic of Georgia. On Dec. 31, the Pentagon transferred three Yemenis — Asim Thabit Abdullah al-Khalaqi, Muhammad Ali Husayn Khanayna and Sabri Mohammed Ibrahim Al Qurashi — to Kazakhstan.

All three had been captured by Pakistani troops in 2001 and handed over to U.S. authorities. They were at Guantanamo for more than 12 years and were recommended for release almost five years ago by Obama’s national security team.

Helene Cooper, New York Times

© 2015 The New York Times Company