WASHINGTON - Members of Congress urged the Pentagon yesterday to declassify its data on sectarian killings, just days before General David Petraeus, the top US commander in Iraq, is expected to report a dramatic decrease in the level of violence between the Sunni and Shi'ite sects.
Petraeus reportedly told an Australian newspaper that the violence had plunged by 75 percent. But analysts question whether the figure is credible.
Yesterday, David Walker, the comptroller general for the Government Accountability Office, told the Senate Armed Services Committee that the methods the Pentagon used to compile its data were too subjective and inconsistent to be meaningful. Walker told the committee that his office "could not get comfortable" with the way the Pentagon calculated such a steep drop in sectarian violence.
Reducing the sectarian violence was President Bush's goal when he announced that 30,000 more troops would be sent to stabilize Iraq. Since the February 2006 bombing of a Shi'ite shrine in Samarra, thousands of Iraqi civilians have died in a cycle of reprisal killings between the two sects, which has threatened to tear the country apart.
But analysts say that it is difficult to test assertions that the violence has dropped dramatically because no independent agency collects comprehensive, consistent statistics. Much of the Pentagon's data and methodology is classified - as is the GAO's comprehensive rebuttal. Estimates of sectarian killings in Iraq, as well as total civilian casualties from all causes, vary widely.
The Pentagon's own data show significant changes over time in their estimates of sectarian killings.
In March, the Pentagon's quarterly report estimated that there were about 1,300 sectarian slayings across Iraq in December 2006, when the sectarian violence was at its peak. But in its June report, the Pentagon revised the December 2006 death toll to more than 1,600. That change makes the decline to about 600 in April - after the surge began - even more dramatic.
Petraeus appeared to increase the December 2006 figure yet again this week in an article that the White House e-mailed to reporters heralding a 75 percent plunge in sectarian killings.
"It's a bit macabre," Petraeus is quoted as saying in the Australian newspaper, "but some areas were literally on fire with hundreds of bodies every week and a total of 2,100 in the month of December '06, Iraq-wide."
But 2,100 sectarian killings is a far higher figure than either of the Pentagon's publicly released estimates for that month.
"I have no idea why Petraeus would have put the number at 2,100," said Ilan Goldenberg, executive director of the National Security Network, a group of left-leaning national security analysts. "It is completely inconsistent with the Pentagon's own numbers unless he is counting apples and oranges."
A Pentagon spokesman, Lieutenant Todd Vician, said "a backlog in unprocessed incident reports at the Iraqi National Command Center" led to the first revision of the December 2006 estimate of sectarian deaths. He did not say why Petraeus changed the estimate again.
A spokesman for Petraeus's office in Washington did not return messages requesting comment.
Anecdotal evidence from officials in Baghdad and media reports suggest that the sectarian violence has declined in recent months. The Pentagon's monthly estimates of sectarian killings in spring 2007, when the troop increase began, tracks closely with the number of unidentified bodies found around the country and reported by the media.
A Globe review of news stories compiled by icasualties.org, an independent website that relies heavily on Reuters reports to record casualties in Iraq, shows that the number of unidentified bodies that have been reported found in the streets rises and falls in the same general pattern as the Pentagon's data on sectarian deaths - but the Pentagon's declines are far steeper. In December 2006, at least 858 bodies were reported found in Iraq.
In July, 655 bodies were discovered, and 503 were found last month, according to the tally of media reports.
Walker, however, cautioned that "even if there is a trend, one needs to understand why." Fewer sectarian deaths, he said, could mean that sects in formerly mixed areas have killed their rivals or driven them out.
Iraq's ambassador to the United States, Samir Sumaida'ie, acknowledged yesterday that a number of factors, including increased "homogeneity," had led to a drop in the rate of sectarian killings.
But he said the increase in troops has helped.
"There used to be gangs of militias roaming around the streets, especially at night, dressed in black or whatever color they prefer, and terrorizing whole neighborhoods," he said in a C-SPAN interview set to air tomorrow. "That has all but stopped."
However, Said Arikat, a spokesman for the United Nations in Baghdad, said that sectarian cleansing by Shi'ite death squads is continuing. People are fleeing in greater numbers that ever, he said.
"Despite the surge, despite the efforts being conducted, people are still fleeing," he said. "Bodies are still being found. Baghdad is definitely becoming a Shi'ite city. Sunnis are fleeing." Aside from Palestinians and Afghans, Iraqis now make up the largest refugee population on earth.
Wayne White, a former State Department intelligence analyst on the Middle East, said that most indicators he has seen lead him to believe that such slayings have declined.
But the big question, he said, is whether sectarian killings will stay at those levels when the United States reduces its troop presence in the city.
"Will sectarian violence simply rebound?" White said. "I fear the answer is 'yes.' "
Globe correspondent Stephanie Vallejo contributed to this report.