Senate Majority Leader Mitch McConnell, R-Ky., says the Obama administration, in its zeal to close Guantanamo, is sending "experienced, hardened terrorists" back into the fight against the United States.

In remarks on the Senate floor Tuesday, McConnell argued that it is "the wrong time" to release fighters who he says have been judged "likely" to resume hostilities.

On Monday, the Pentagon announced the transfer of Salem Abdu Salam Ghereby and Omar Khalif Mohammed Abu Baker Mahjour Umar from the U.S. military detention facility at Guantanamo Bay to the government of Senegal.

McConnell claims both detainees are explosives experts who were longtime supporters of al Qaeda.

"According to records that have been made public, one of those detainees, a former associate of Osama Bin Laden, is likely to re-engage in hostilities. The other detainee was previously assessed as likely to return to the fight," McConnell said.

Pentagon Spokesman Capt. Jeff Davis defended the transfer Tuesday as consistent with Defense Secretary Ash Carter's criteria to ensure that detainee transfers don't pose a danger to the U.S.

"The secretary takes very seriously his not only statutory requirement, but also his moral requirement to the American people to ensure that these detainees don't present a threat to U.S. persons in the future," Davis told reporters at the Pentagon.

Davis declined to say what provisions were made with the government of Senegal to make sure the former detainees don't use their bomb-making skills on behalf of al Qaeda or other terrorist groups.

"We make very specific agreements with these countries on these assurances, but we don't get into the details of those, just like diplomatic matters," Davis said.

McConnell, the senior Republican in the Senate, argued that the release is irresponsible in the wake of rising violence and terror attacks.

"This comes at a time when al Qaeda in the Arabian Peninsula has exploited the war within Yemen to secure a safe haven, and the Nusra Front within Syria is exploiting the civil war there to carry on al Qaeda's mission," he said.

The transfer of the two detainees brings the number of prisoners at Guantanamo to 89.