As if the release of more than 75,000 classified documents on the Afghanistan war weren't enough, the whistleblower group behind the leak said Monday that another 15,000 are on the way -- sending officials scrambling to screen the documents as they emerge for "potential damage" to U.S. security.

Pentagon spokesman Col. Dave Lapan told reporters Monday that the military takes the leak "very seriously" and is in the process of reviewing the information. Wikileaks.org, the website that released the records, claims the full set is more than 91,000 pages -- Lapan said it could take "weeks" to review all of them as they are released.

"As they are made available, we will be looking at them to try to determine the potential damage to lives of our service members and our coalition partners, whether they reveal sources and methods and any potential damage to national security," he said.

WikiLeaks founder Julian Assange said he released 76,000 documents and that the remaining 15,000 were being withheld pending further review. He said some would be released and others would be withheld until it is safe to release them.

Earlier, the Obama administration said the document dump would not hurt the war effort, but condemned the release as "irresponsible" and said Wikileaks "made no effort" to contact the federal government before releasing them.

A U.S. official warned that much of the material covers "unvarnished, unvetted, uncorroborated reporting" from people in the region who may have "agendas." Officials also accused Wikileaks of having an anti-Afghanistan war agenda.

"Wikileaks seems to have an agenda of its own -- and it goes beyond publishing classified information for the benefit of others to analyze," the U.S. official said. "They purport to be objective at the same time they offer their own opinions of the war. That's truly shameful. No one is denying that there are real challenges in Afghanistan, but you'd never want Wikileaks to be your meteorologist. They see nothing but dark clouds. As we all know, weather cycles are more nuanced than that."

The 91,000 classified U.S. records on the war, marking one of the largest unauthorized disclosures in military history, cover a time period that largely predates the Obama administration as well as the new strategy and surge announced at the end of 2009. They apparently cover a period from January 2004 to December 2009.

The documents cover much of what the public already knows about the troubled nine-year conflict: U.S. special-ops forces have targeted militants without trial, Afghans have been killed by accident and U.S. officials have been infuriated by alleged Pakistani intelligence cooperation with the very insurgent groups bent on killing Americans.

National Security Adviser Gen. James Jones said in a written statement that relations with the Pakistanis and other trouble spots have improved since the end of 2009.

"On December 1, 2009, President Obama announced a new strategy with a substantial increase in resources for Afghanistan, and increased focus on Al Qaeda and Taliban safe-havens in Pakistan, precisely because of the grave situation that had developed over several years," he said.

Jones lambasted Wikileaks.org for releasing the massive trove of documents.

"The United States strongly condemns the disclosure of classified information by individuals and organizations which could put the lives of Americans and our partners at risk, and threaten our national security," he said.

WikiLeaks posted the documents Sunday. The New York Times, London's Guardian newspaper and the German weekly Der Spiegel were given early access to the records.

Assange, who held a press conference in London to address the documents, said Monday his organization has "no reason to doubt the reliability" of the records. He said the records will "shape an understanding" of the war's first six years, though he said the documents did not include any "top secret" information.

He claimed that "there does appear to be evidence of war crimes in this material," in a reference to at least seven reported civilian casualties.

A White House aide said many of the concerns addressed in the documents had been addressed publicly by U.S. officials.

Pakistan's Ambassador Husain Haqqani said the documents "do not reflect the current on-ground realities," in which his country and Washington are "jointly endeavoring to defeat Al Qaeda and its Taliban allies."

Senate Foreign Relations Committee Chairman John Kerry, D-Mass., though, suggested the release could lead to a change in policy. He said in a written statement that "however illegally" the documents were released, they raise "serious questions" about U.S. policy toward the region.

"Those policies are at a critical stage and these documents may very well underscore the stakes and make the calibrations needed to get the policy right more urgent," he said.

The U.S. and Pakistan assigned teams of analysts to read the records online to assess whether sources or locations were at risk.

The Guardian said the documents "fail to provide a convincing smoking gun" for complicity between the Pakistan intelligence services and the Taliban.

The New York Times interpreted the papers differently, saying they reveal that only a short time ago, there was far less harmony in U.S. and Pakistani exchanges.

The Times said the "raw intelligence assessments" by lower level military officers suggest that Pakistan "allows representatives of its spy service to meet directly with the Taliban in secret strategy sessions to organize networks of militant groups that fight against American soldiers in Afghanistan, and even hatch plots to assassinate Afghan leaders."

The leaked records include detailed descriptions of raids carried out by a secretive U.S. special operations unit called Task Force 373 against what U.S. officials considered high-value insurgent and terrorist targets. Some of the raids resulted in unintended killings of Afghan civilians, according to the documentation.

During the targeting and killing of Libyan fighter Abu Laith al-Libi, described in the documents as a senior Al Qaeda military commander, the death tally was reported as six enemy fighters and seven noncombatants -- all children.

Task Force 373 selected its targets from 2,000 senior Taliban and Al Qaeda figures posted on a "kill or capture" list, known as JPEL, the Joint Prioritized Effects List, the Guardian said.

WikiLeaks said the release Sunday "did not generally include top-secret organizations," and that it had delayed the release of the remaining 15,000 documents as part of what it called "a harm minimization process demanded by our source," but said it would release the documents later, possibly with material redacted.

U.S. government agencies have been bracing for a deluge of thousands more classified documents since the leak of helicopter cockpit video of a 2007 firefight in Baghdad. That was blamed on a U.S. Army intelligence analyst, Spc. Bradley Manning, 22, of Potomac, Md. He was charged with releasing classified information this month. Manning had bragged online that he downloaded 260,000 classified U.S. cables and transmitted them to Wikileaks.org.

The Associated Press contributed to this report.