The U.S. has "updated" its efforts to monitor Taliban detainees released from Guantanamo Bay in exchange for an American soldier because of concerns that they may be seeking to return to the battlefield, the White House said Friday.

The five detainees have been in Qatar since being released last year in exchange for Sgt. Bowe Bergdahl . On Thursday, Republican Sen. Lindsey Graham of South Carolina said the men have been in touch with members of the al-Qaida linked Haqqani network.

White House spokesman Josh Earnest said the detainees remain in Qatar and their activities are limited. But he says mitigation efforts "have been updated" to reflect concerns about their contacts with terror groups.

Earnest wouldn't detail the updates but said the U.S. is confident in measures that are in place.

At the Pentagon, spokesman Rear Adm. John Kirby said steps were being taken to mitigate any activity by the former detainees in the future. Although he declined to discuss the details of the agreement with Qatar, Kirby said the U.S. remains confident that "the assurances we received are sufficient enough to help us mitigate any future threat that these individuals might pose."