WASHINGTON – White House officials and their allies in Afghanistan and Pakistan sought Monday to play down the political and military impact of the unauthorized release of thousands of classified Afghan war documents, saying they portray a reality on the ground that is already largely known.

The secret documents released by the group WikiLeaks.org reveal, in often excruciating detail, the struggles U.S. troops have faced in battling an increasingly potent Taliban force and in working with Pakistani allies who also appear to be helping the Afghan insurgency.

The more than 91,000 classified documents — most of which consist of low-level field reports — represent one of the largest single disclosures of such information in U.S. history. WikiLeaks gave the material to the New York Times, the British newspaper the Guardian and the German magazine Der Spiegel several weeks ago on the condition that they not be published before Sunday night, when the group released them publicly.

Press secretary Robert Gibbs condemned the leak of the documents, calling their publication “a concerning development in operational security” that “poses a very real and potential threat to those that are working hard every day to keep us safe.”

But Gibbs rejected the idea that the documents reveal anything fundamentally new about the war effort, or that the leak is causing any political dilemma for the administration as it pushes ahead with the war policy the president settled on last December.

“What is known about our relationship and our efforts in both Afghanistan and Pakistan are not markedly changed by what is in these documents,” Gibbs said.

“There’s no broad new revelations in this.”

President Obama did not respond to questions about the leak after appearing in the Rose Garden to make an unrelated statement to the press.

Pentagon spokesman Col. Dave Lapan said officials are conducting a review of the documents “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.”

The probe, he told reporters on Monday, will take “days, if not weeks.”

Gibbs chided the people who run the WikiLeaks site for failing to give the administration the chance to purge the documents of names or operational details that might put people in danger.

“There are ways in which one can disapprove a policy without breaking the law and putting in potential danger those who are there to keep us safe,” Gibbs said.

In Afghanistan, officials expressed dismay and alarm over the unauthorized release of information. In Pakistan, officials disputed claims made in the documents that the Pakistani intelligence agency had collaborated with the Taliban.

“These allegations are always repeated,” said Pakistan’s ambassador to Afghanistan, Mohammad Sadiq. “I don’t see anything new.”

Wahid Omar, a spokesman for Afghanistan President Hamid Karzai, told reporters in Kabul that “the president’s immediate reaction was that most of this is not new.”

On Capitol Hill, early reaction pointed to a potential political danger for the Obama administration, which has already seen some erosion of support for its Afghanistan war policy.

Sen. John F. Kerry, D-Mass., a key ally for the president, said the documents raise concerns.

“However illegally these documents came to light, they raise serious questions about the reality of America’s policy toward Pakistan and Afghanistan,” Kerry said in a statement.

Other Democrats appeared to echo the White House message more closely, saying the documents do not substantially alter the debate over the president’s war policy in Afghanistan.

“These leaked reports pre-date our new strategy in Afghanistan and should not be used as a measure of success or a determining factor in our continued mission there,” said House Armed Services Committee Chairman Ike Skelton, D-Mo.

The revelations have the potential of complicating final negotiations in Congress over a $33 billion war funding bill that would finance the U.S. troop surge in Afghanistan.

The package has cleared the Senate but stalled in the House when liberal Democrats, some of whom oppose the troop buildup, attached unrelated economic recovery assistance.

Covering the period from January 2004 through December 2009, when the Obama administration began to deploy more than 30,000 additional troops into Afghanistan and announced a new strategy, the documents provide new insights into a period in which the Taliban was gaining strength, Afghan civilians were growing increasingly disillusioned with their government, and U.S. troops in the field often expressed frustration at having to fight a war without sufficient resources.

The documents disclose for the first time that Taliban insurgents appear to have used portable, heat-seeking surface-to-air missiles to shoot down U.S. helicopters.

Heat-seeking missiles, which the United States provided to the anti-Soviet Afghan fighters known as mujaheddin in the 1980s, helped inflict heavy losses on the Soviet Union until it withdrew from Afghanistan in 1989.

One report from the spring of 2007 refers to witnesses who saw what appeared to be a heat-seeking missile destroy a CH-47 transport helicopter.

The Chinook crash killed five Americans, a British citizen and a Canadian.

Even though the initial U.S. report stated that the helicopter was “engaged and struck with a missile,” a NATO spokesman suggested that small-arms fire was responsible for bringing it down.

Although the use of such weapons by the Taliban appears to be very limited, the disclosure that relatively low-tech insurgents had acquired such arms would have fostered the impression that the Afghan war effort was faltering at a time when U.S. fatalities in Iraq were at record levels and the Bush administration was struggling to maintain support for the Iraq war.

Many of the documents posted by WikiLeaks suggest that Pakistan’s spy service might be helping Afghan insurgents plan and carry out attacks on U.S. forces in Afghanistan and their Afghan government allies. A few reports also describe cooperation between Pakistani intelligence and fighters aligned with al-Qaida.

U.S. intelligence concluded a number of years ago that Pakistan retained its ties with Taliban groups, intelligence officials said.

Late last year, Obama warned in a letter to Pakistan’s President Asif Ali Zardari that the United States would no longer put up with the contacts.

But the documents appear to suggest that Pakistan’s spy agency, known as the Inter-Services Intelligence directorate or ISI, might have assisted insurgents in planning some attacks.

The Pakistani government denied the allegations in the classified intelligence documents.

“These reports reflect nothing more than single-source comments and rumors, which … are often proved wrong after deeper examination,” said Husain Haqqani, Pakistan’s ambassador to the United States.WikiLeaks founder Julian Assange said the release of documents was just the beginning. He told reporters in London that some 15,000 more files on Afghanistan were still being vetted by his organization.