The report given to the Senate Foreign Relations Committee said only two of nine security goals given to the government of Iraqi Prime Minister Nouri al-Maliki had been met by the end of July and two others partially met.
GAO Comptroller General David Walker told the committee Tuesday that he stands by the report and called the Iraqi government "dysfunctional," The Washington Post reported.
However, two senior military sources told the newspaper the report was flawed.
"They use the end of July as the data and evidentiary cutoff and therefore are not taking into account any gains in any of the benchmarks that may have become more clear throughout August," one official said.
Another told the Port "we absolutely disagree with their characterization of sectarian violence," as he said the attacks had fallen significantly during the year, the report said.
The report came days before a report on security and political developments will be given to Congress by U.S. Army Gen. David Petraeus, the top U.S. commander in Iraq, and U.S. Ambassador to Iraq Ryan Crocker.