A U.S. government official told ABC News the private contractors "don't kick down doors" but only fulfill a "security role" on certain CIA missions.
The new CIA director under the Obama administration, Leon Panetta, has continued a "rigorous look" at the use of contractors and a "thorough review" of Blackwater's contracts.
Said Little, "Earlier this year, Director Panetta ordered the end of one Blackwater contract and the transition of those activities to government personnel. In addition, he ordered a review of all Blackwater contracts."
"At this time," said Little, "Blackwater is not involved in any CIA operations in other than a security or support role."
Pentagon spokesman Geoff Morrell said the allegation that private contractors were used in combat situations by the American military was "bogus, nothing more than a wild and unsubstantiated allegation." He said there was no evidence that the military had ever contracted with Blackwater for such missions.
Morrell did not respond to specific questions about the top-secret Vibrant Fury operation in 2006 that allegedly recruited Blackwater operatives.
"If you have a team of private contractors who are going into Pakistan with the approval of the United States government to engage in combat, then you have very serious international and domestic problems," said Professor Turley.
Blackwater, now re-named Xe, has a "select" program within its operation that helped to staff some of the expanded and more difficult roles in the two war zones, according to U.S. military officials, former U.S. intelligence officers and a person with knowledge of Blackwater operations.
A 2007 on-line recruitment advertisement for the Blackwater USA select program described the openings as positions in a "Mobile Security Contract in support of a U.S. government agency."
Candidates were required to be able to maintain a Top Secret clearance and have "one year of experience in Iraq, Afghanistan or other High Threat Environment."
A U.S. Army officer who ran human intelligence collections activities in Afghanistan in 2003, Tony Shaffer, says he never worked directly with Blackwater personnel but frequently encountered them in secret operations run by the military and the CIA.
"I actually met with the CIA and Blackwater operatives who were working together, totally hand in glove, to conduct operational planning and support of their objectives, which are paramilitary operations along the border," said Shaffer, then a Major but now a Lieutenant Colonel who teaches at the Center for Advanced Defense Studies.
"The idea was to bring to bear additional resources for specific special operations missions," he said. "The purpose for that, in my judgment, may have been to avoid some level of oversight."
In the case of Operation Vibrant Fury, military personnel say the decision to request Blackwater personnel came after a request for military "tier one" operatives was denied.
A spokesperson for Blackwater said the company was unaware of any operation with the code name Vibrant Fury.
The mission was to raid, destroy and kill al Qaeda members at a camp in Pakistan where guards for Osama bin Laden and Ayman al Zawahiri were believed to be training, according to the military planner.
A second person briefed on the operation confirmed Blackwater agreed to provide operatives for the military special forces.