Washington (CNN) -- The whistle-blower website WikiLeaks published nearly 400,000 classified military documents from the Iraq war on Friday, calling it the largest classified military leak in history.

The latest round of leaked documents provides a new picture of how many Iraqi civilians have been killed, a new window on the role that Iran has played in supporting Iraqi militants and many accounts of abuse by Iraqi's army and police, according to The New York Times.

The Times was one of a handful of news organizations that was provided early access to the papers.

According to new documents, the vast majority of slain civilians were killed by other Iraqis.

The U.S. military is notifying Iraqis named in the documents, Pentagon Press Secretary Geoff Morrell told CNN.

"There are 300 names of Iraqis in here that we think would be particularly endangered by their exposure," he said. "We have passed that information on to U.S. Forces Iraq. They are in the process right now of contacting those Iraqis to try to safeguard them."

The Pentagon had not previously warned Iraqi civilians who have cooperated with the United States that their names may be posted on the Internet.

"We don't want to start notifying people and then find out that their names aren't in any of these documents that are released," Col. David Lapan, a top Pentagon spokesman, said earlier Friday. "Why put people through the trouble and the concern for no reason?"

The Pentagon denounced the release, which WikiLeaks said comprised 391,832 reports.

"This is all classified secret information never designed to be exposed to the public," Morrell told CNN Friday. "Our greatest fear is that it puts our troops in even greater danger than they inherently are on these battlefields. That it will expose tactics, techniques and procedures -- how they operate on the battlefield, how they respond under attack, the capabilities of our equipment ... how we cultivate sources (and) how we work with Iraqis."

After a similar release of 77,000 classified documents from the war in Afghanistan, Chairman of the Joint Chiefs of Staff Adm. Mike Mullen said WikiLeaks "might already have on their hands the blood of some young soldier or that of an Afghan family."

Morrell echoed that sentiment Friday.

"We know in the aftermath of the Afghan document leak that the Taliban and others spoke publicly, encouraging their members to mine that database -- our intelligence confirmed that fact," he told CNN. "Now you will have virtually half a million classified secret documents in the public domain which our enemies clearly intend to use against us.

"That can endanger the lives of American forces, not just in Iraq and Afghanistan, but around the world," Morrell said.

WikiLeaks has shown a much heavier hand redacting the new round of documents compared to its previous publication of documents.

Editor-in-chief Julian Assange told CNN's Atika Shubert the site was more "vigorous" this time compared to the Afghanistan process.

Read more on WikiLeaks' redaction of information

An initial comparison of a few documents redacted by WikiLeaks to the same documents released by the Department of Defense shows that WikiLeaks removed more information than the Pentagon.

The documents detail Iran's role in supplying Iraqi militia fighters with weapons, including the most lethal type of roadside bomb.

Field reports released Friday assert that Iraqi militants traveled to Iran for training as snipers and in using explosives, according to the Times. Iran's Quds Force urged Iraqi extremists it was working with to kill Iraqi officials, the Times reported.

CNN was offered access to the documents in advance of the release but declined because of conditions that were attached to accepting the material.

According to an analysis by the Guardian, a British newspaper, the documents detail torture, summary executions and war crimes.

U.S. authorities failed to investigate hundreds of reports of abuse, torture, rape and murder by Iraqi police and soldiers, the documents show, according to the Guardian.

The Times said that hundreds of reports of beatings, burnings and lashings suggested that "such treatment was not an exception." Most abuse cases contained in the new batch of leaks appear to have been ultimately ignored, the paper said.

The Times said that military rules require forces to report abuse to Iraqi authorities, but suggested that there was little follow-up on abuse reports.

The group Iraq Body Count said that the new documents reveal 15,000 previously unknown civilian deaths, raising the group's civilian death toll to 122,000.

"It's the largest single addition to our database since we began it," the anti-war group's co-founder, John Sloboda, told CNN.

WikiLeaks' Assange told CNN in an exclusive interview Friday that the new round of field reports shows "compelling evidence of war crimes" committed by forces of the U.S.-led coalition and the Iraqi government.

The Pentagon's Morrell rebutted that charge.

"We vetted every single one of the documents, word by word, page by page," Morrell told CNN, saying the vetting began in July. "There is nothing in here which would indicate war crimes. If there were, we would have investigated it a long time ago."

A group of 120 Defense Department experts has been poring over hundreds of thousands of "Significant Action Reports" that they expected to be posted to the WikiLeaks website.

In a news release, the group said the documents detail 109,032 deaths in Iraq, encompassing 66,081 civilians, 23,984 insurgents, 15,196 Iraqi government forces and 3,771 coalition forces, according to the classifications used by the U.S. military.

Assange said the documents contained more than 1,000 reports on the torture or abuse of detainees by Iraqi government forces and that he expects that 40 wrongful death lawsuits will be filed as a result of the new leaks.

He dismissed concerns that the publication of the documents could endanger U.S. troops and Iraqi civilians, asserting that the Pentagon "cannot find a single person that has been harmed" due to WikiLeaks' previous release of 76,000 pages of documents related to the U.S.-led war in Afghanistan.

"We strongly condemn the unauthorized disclosure of classified information and will not comment on these leaked documents other than to note that 'significant activities' reports are initial, raw observations by tactical units," the Department of Defense said in a Friday statement. "They are essentially snapshots of events, both tragic and mundane, and do not tell the whole story. That said, the period covered by these reports has been well-chronicled in news stories, books and films and the release of these field reports does not bring new understanding to Iraq's past.

"However, it does expose secret information that could make our troops even more vulnerable to attack in the future," the statement continued. "Just as with the leaked Afghan documents, we know our enemies will mine this information looking for insights into how we operate, cultivate sources, and react in combat situations, even the capability of our equipment. This security breach could very well get our troops and those they are fighting with killed."

Ryan Crocker, former U.S. Ambassador to Iraq, said this week he is concerned for the safety of the Iraqis who may be mentioned.

"What I'd really be worried about in this context, we're not fighting a hot war," Crocker said in remarks at the Center for Strategic and International Studies on Tuesday. "It's not the same set of issues in Afghanistan, although there may be some carryover. I'd really be worried if, as looks to be the case, you have Iraqi political figures named in a context or a connection that can make them politically and physically vulnerable to their adversaries.

"It just has an utterly chilling effect on the willingness of political figures to talk to us, not just in Iraq, anywhere in the world. And I think a hugely irresponsible step on the part of WikiLeaks. Just in a different sense than we saw in Afghanistan, this, too, is going to put lives at risk needlessly and irresponsibly."

CNN's Larry Shaughnessy contributed to this report.