The Pentagon is seen in this aerial view in Washington, in this March 27, 2008 file photo. The WikiLeaks website appears close to releasing what the Pentagon fears is the largest cache of secret U.S. documents in history _ hundreds of thousands of intelligence reports compiled after the 2003 invasion of Iraq. In a message posted to its Twitter page on Thursday Oct. 21, 2010, the organization said there was a "major WikiLeaks press conference in Europe coming up."Charles Dharapak/The Associated Press
The Pentagon said on Friday it does not expect big surprises from an imminent release of up to 500,000 Iraq war files by WikiLeaks, but warned that U.S. troops and Iraqis could be endangered by the file dump.
If confirmed, the leak would be much larger than the group's record-breaking publication of more than 70,000 Afghan war documents in July, which stoked debate about the nine-year-old conflict but did not contain major revelations.
It was the largest security breach of its kind in U.S. military history.
Colonel Dave Lapan told reporters that a Pentagon team had reviewed the Iraq war files it believes WikiLeaks has, spanning a time period between 2003 and 2010.
He described them as largely "ground-level" field reports which could expose the names of Iraqi individuals working with the United States and give insight to Iraqi insurgents about U.S. operations, similar to the Afghan war files.
"Our concern is mostly with the threat to individuals, the threat to our people and our equipment," Lapan said.
"But in terms of the types of incidents that are captured in these reports, where innocent Iraqis have been killed, where there are allegations of detainee abuse, all of these things have been very well chronicled over time."
Although the Iraq conflict has faded from public debate in the United States in recent years, the document dump threatens to revive memories of some of the most trying times in the war, including the Abu Ghraib prisoner abuse scandal.
It could also renew debate about foreign and domestic actors influencing Iraq, which has been wrestling with a political vacuum since an inconclusive election in March.
One source familiar with the Iraq documents said they are likely to contain revelations about civilian casualties.
Lapan said he did not expect the WikiLeaks dump to include images or video files.
WikiLeaks says it is a non-profit organization funded by human rights campaigners, journalists and the general public. But the Pentagon has demanded it return classified information and critics have questioned its perceived anti-war agenda.
At the time of the Afghan war leak, the top U.S. military officer, Admiral Mike Mullen, warned that WikiLeaks may have the blood of U.S. soldiers and Afghan civilians on its hands because it had leaked documents naming U.S. collaborators.
Still, U.S. Defense Secretary Robert Gates said in an August letter to the head of the Senate Armed Services Committee that the Afghan leak had not revealed any sensitive intelligence sources or methods.
Gates however said disclosing the names of co-operating Afghans, who could become targets for the Taliban, could cause "significant harm or damage" to U.S. national security interests.
So far the investigation into the Afghan war leak has focused on Bradley Manning, who worked as an Army intelligence analyst in Iraq. Manning is already under arrest and charged with leaking a classified video showing a 2007 helicopter attack that killed a dozen people in Iraq, including two Reuters news staff employees.
The Pentagon, citing the criminal investigation, has refused to discuss the Manning case.