This June 7, 2014, photo shows the entrance to Camp 5 and Camp 6 at the U.S. military's Guantanamo Bay detention center, at Guantanamo Bay Naval Base, Cuba. (Ben Fox/AP)

Defense Secretary Jim Mattis met with troops at Guantanamo Bay, Cuba, on Thursday, the first time an American defense chief has visited the U.S. naval outpost since scores of terrorism suspects were imprisoned there in 2002.

Then-Defense Secretary Donald H. Rumsfeld was among senior officials to visit Guantanamo in January of that year, just as the George W. Bush administration was flying in shackled, hooded suspected militants in the months after the 9/11 attacks.

The naval station's prison, which housed more than 700 inmates at its peak, became a symbol of the U.S. excesses that followed those attacks, including detainee torture, extrajudicial imprisonment and opaque, slow-moving military trials.

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Col. Robert Manning III, a Pentagon spokesman, said Mattis made the visit to thank service members during the holidays but was not scheduled to visit the prison facilities or meet with officials responsible for the 41 detainees remaining there.

The visit highlights the Trump administration's evolving approach to the prison and to prosecuting and detaining terrorism suspects.

Since taking office, President Trump appears to have backed off earlier promises to fill Guantanamo with "bad dudes." His administration has taken little visible action to renew military detentions there or to overcome the hurdles holding up the military commissions that are supposed to try suspects in the 9/11 attacks.

Trump's predecessor, President Barack Obama, failed to deliver on his promises of shuttering Guantanamo, and lawmakers have consistently opposed moving inmates to U.S. facilities for detention or trial.

"Guantanamo remains a symbol of torture and illegal and illegitimate detention and trials," said Raha Wala, director of national security advocacy at ­Human Rights First.

"So it's unsurprising that the Trump administration is figuring out what prior administrations already knew: Guantanamo is a big headache and an unattractive option compared to detention using normal procedures," Wala said.

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While political leaders including Attorney General Jeff Sessions, who visited Guantanamo in July, have voiced support for continuing detentions at Guantanamo, resistance from agencies involved in trying and housing terrorism suspects appears to have helped quash any steps to renew detentions there.

Trump appeared to reference those challenges after a terrorism attack in New York last month.

After initially saying he would like to see suspect Sayfullo Saipov at the military prison, the president later tweeted that he "would love to send the NYC terrorist to Guantanamo but statistically that process takes much longer than going through the Federal system."

Dan Lamothe, Julie Tate, Matt Zapotosky and Devlin Barrett contributed to this report.