The men, all employees of Blackwater Worldwide, were indicted this week by a federal grand jury. They were involved in killing 17 Iraqi civilians in Nisour Square in September 2007.

The federal government has not identified the defendants. The Washington Post, citing lawyers and sources, said they are Evan Liberty, 26, of Rochester, N.H.; Nick Slatten, 25, of Sparta, Tenn.; Dustin Heard, 27, of Maryville, Tenn.; Donald Ball, 26, of Salt Lake City; and Paul Slough, 29, of Sanger, Texas.

All are veterans of the Army or Marines and all, except Liberty, had served in Iraq before joining Blackwater, the newspaper said.

"The indictment is an effort by bureaucrats in Washington to second-guess split-second decisions made by honorable men during a firefight in the most dangerous neighborhood in the world," Tom Connolly, Slatten's lawyer, said.

However, an FBI investigation has determined that at least 14 of the 17 deaths could not be justified, The New York Times said Friday.

The lawyers said they would argue that U.S. courts have no jurisdiction in the case. The contractors had immunity from Iraqi prosecution.