Sen. Dianne Feinstein (D-Calif.) said she was not satisfied with reassurances from Secretary of State John Kerry that the five Taliban leaders released in exchange for a U.S. soldier pose no threat to Americans.
"And we have no information on how the United States is actually going to see that they remain in Doha, that they make no comments, that they do no agitations."
With the war in Afghanistan coming to a close and all troops planned to return by the end of 2016, Feinstein said there's still significant danger there.
"What's unfortunate is that I see no sign of the Taliban relenting," she said.
As chairwoman of the Senate Intelligence Committee, Feinstein has been one of the loudest Democratic critics of the Obama administration for failing to brief members of Congress before releasing Army Sgt. Bowe Bergdahl.
She said the lack of communication from the White House on the situation had sowed some doubts for her.
"It's hard to be comfortable when you really haven't been briefed on the intricacies of carrying out this agreement," she said, again in response to Kerry's reassurances.
The White House has said it didn't brief members of Congress out of concern that any leaks could jeopardize Bergdahl's life, and that it's not common protocol to brief Congress on an ongoing operation. But Feinstein pushed back against that assertion.
"[Senate Intelligence Committee Ranking Member Saxby] Chambliss (R-Ga.) and I have been briefed on operations underway. We understand the security of that, we have never violated that, but at least you have some knowledge and you can make some comment," she said.
"That's never been the case with this particular situation. So it hits us as a real surprise."
Chambliss, speaking just after Feinstein on "Face the Nation," said that he was alerted to the situation with a phone call on Monday night, after Bergdahl was released on Saturday.
"This administration's acted very strangely about this, Bob, and it's kind of puzzling as to why they didn't let us know in advance this was happening," he said.