Even though it wants to close it, the US is “stuck” with the Guantanamo Bay detention centre, said Defence secretary Robert Gates.
He said the US wanted to send up to 70 prisoners home, but countries would either not take them, or could not be trusted to.
Human rights groups say it doesn’t meet international legal standards, and have long argued for its closure.
Currently there are about 270 detainees in the prison in Cuba.
At the US Senate hearing, Mr Gates said : “the brutally frank answer is that we’re stuck. We have a serious ‘‘not in my backyard’ problem”.
“Either their home government won’t accept them or we’re concerned that the home government will let them loose once we return them home” he added.
Then he asked :“What do you do with that irreducible 70 or 80 who you cannot let loose but will not be charged and will not be sent home?”
According to the Pentagon, 36 former inmates, who were released, are “confirmed or suspected of having returned to terrorism”.
Dianne Feinstein, Democratic Party Senator, told Mr Gates : “nothing you have said absolves the enormous loss of credibility we have in the eyes of the world.”
“We are being called hypocrites, that we have double laws, laws for some, and no laws for others.”
Mr Gates’s attitude has been condemned by Rights groups.
“The secretary’s comments really are astounding in light of the money, resources and personnel of the department of defence”, Vincent Warren, executive director of the Centre for Constitutional Rights, told Reuters news agency.