Military Officials in Iraq Fault GAO Report

The letter might be only the start of a rebellion against the leaders of both parties. Another version of the letter circulating on Capitol Hill demands a House vote on bipartisan legislation that would give the president 60 days to present to Congress a plan to begin withdrawing troops.

Walker, the GAO chief, denied that substantive changes in the report had been made under pressure. "The only thing we really did was we went to a 'partially met' on a couple, on one of which I'd made the judgment . . . independently of [military] comments; the other of which they provided us additional information that we did not have previously," he said in congressional testimony.

The GAO concluded that all forms of violence remain high in Iraq -- causing senior military officials to complain that the report did not consider statistics for August, when, they said, trends in sectarian violence and the performance of the Iraqi security forces improved.

"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.

The military officials, who spoke on the condition of anonymity because Petraeus will give the official military position in testimony Monday, took particular exception to the GAO statement that a drop in sectarian attacks could not be confirmed. The final version of the report softened the draft's initial conclusion that "U.S. agencies differ on whether such violence has been reduced," saying instead that "measuring such violence may be difficult since the perpetrator's intent is not clearly known."

One military official called even the revised version "factually incorrect," saying that "we absolutely disagree with their characterization of sectarian violence." Such attacks have fallen significantly this year, he said.

But Walker said the GAO received different assessments of the levels of violence. The report, he noted, recommended that the administration reflect such divergence in its own reports. It was unclear whether sectarian attacks had dropped, he said, "since it is difficult to measure intentions and there are various measures of sectarian violence from different sources. . . . Some show increases, some show decreases, and some show inconsistent patterns."

Walker said the GAO consulted with the military until Thursday. "We asked for, but did not receive, the information through the end of August," he said. "But we obtained their views for where the situation was . . . as of August 30th."

Staff writer Jonathan Weisman contributed to this report.