The Pentagon on Tuesday defended its initial response to the terrorist attack on U.S. facilities in Benghazi, Libya, denying claims by a Fox News source that the military could have successfully sent a special forces team in time to help.

Rep. Elijah Cummings, D-Md, first wrote to the Defense Department last week seeking a response to Fox News reporting that anonymously quoted a special operator involved with Benghazi.

Cummings asked Defense Secretary Chuck Hagel to “provide an unclassified response to these specific allegations” that the U.S. military had a team in Europe and could have responded quickly.

Elizabeth King, the assistant secretary of Defense for legislative affairs responded to Cummings in a letter Tuesday, saying a special force team was training in Croatia but was able to do little more than "pre-positioning" in Italy “because exact conditions on the ground in Benghazi were unknown."

"From the moment the (team) was ordered to move, it did not stand down until after all personnel (including the fallen) had been evacuated from Benghazi in a little over 12 hours after the initiation of the attack," King said.

The Pentagon statement further amplifies the contrasts between two opposing versions of what happened during the attack, with critics saying the Obama administration is engaged in a cover-up.

The special operator quoted by Fox News had contradicted claims by the Obama administration and a State Department review that said there wasn’t enough time for U.S. military forces to have intervened in the Sept. 11 attack, in which U.S. Ambassador to Libya Chris Stevens, an embassy employee and two former Navy SEALs working as private security contractors were killed.

Three whistle-blowers are scheduled to testify Wednesday on Capitol Hill about the administration's response to the attack and officials' actions in the immediate aftermath.

Fox News' Chad Pergram and Adam Housley contributed to this report.