The Times said WikiLeaks released the documents to The Guardian of Britain, Le Monde of France and Der Spiegel of Germany. One condition was an embargo until Friday.
In an overview of the information, the Times said the documents provide "insight, texture and context" rather than major new information. For example, it said the documents highlight that the number of Iraqi civilian deaths was much higher than the Bush administration acknowledged, that abuse of detainees by Iraqi security forces was common and often ignored by their U.S. partners, and that the Iraqi military often supported Shiite militia groups.
The documents also show how the United States came to depend increasingly on private contractors to perform what had been military responsibilities in previous conflicts.
WikiLeaks has not identified the source of the documents. A U.S. soldier who worked as an intelligence analyst, Pfc. Bradley Manning, has been charged with leaking classified information.
The Times said it told the Pentagon what it was planning to publish and how information had been edited or removed. It said officials did not urge any changes.
Geoff Morrell, the Defense Department's press secretary, said terrorist groups have been "mining" documents on Afghanistan that were released earlier and expects the same thing to happen with the Iraqi ones.
"We deplore WikiLeaks for inducing individuals to break the law, leak classified documents and then cavalierly share that secret information with the world, including our enemies," he said.