U.S. intelligence and defense officials suspect that as many as 20-30 released Gitmo detainees have joined ISIS, al Qaeda and other militant groups inside Syria.

Sen. John McCain (R-Ariz.) went “On The Record” tonight to weigh in.

Soldier Who Took Part Bergdahl Search: 'He Is a Deserter'

He mentioned the five Gitmo detainees swapped for Sgt. Bowe Bergdahl, telling Greta Van Susteren, “I guarantee you they reentered the fight.”

“The eagerness with which this administration wants to get these people out of Guantanamo has clearly overridden good sense and a real concern for the lives of American men and women who are serving,” he said.

'He's Not a Hero': 6 of Bowe Bergdahl's Platoon Members Speak Out

Watch more above.