WASHINGTON - A new American intelligence assessment on the Afghan war predicts that the gains the United States and its allies have made during the last three years are likely to have been significantly eroded by 2017, even if Washington leaves behind a few thousand troops and continues bankrolling the impoverished nation, according to officials familiar with the report.

The National Intelligence Estimate, which includes input from the country's 16 intelligence agencies, predicts that the Taliban and other power brokers will become increasingly influential as the United States winds down its longest war in history, according to officials who have read the classified report or received briefings on its conclusions. The grim outlook is fueling a policy debate inside the Obama administration about the steps it should take over the next year as the U.S. military draws down its remaining troops.

The report predicts that Afghanistan would likely descend into chaos quickly if Washington and Kabul don't sign a security pact that would keep an international military contingent there beyond 2014 - a precondition for the delivery of billions of dollars in aid that the United States and its allies have pledged to spend in Afghanistan over the coming years.

"In the absence of a continuing presence and continuing financial support," the intelligence assessment "suggests the situation would deteriorate very rapidly," said one U.S. official familiar with the report.

That conclusion is widely shared among U.S. officials working on Afghanistan, said the official, who was among five people familiar with the report who agreed to speak on the condition of anonymity to discuss the assessment.

Some officials have taken umbrage at the underlying pessimism in the report, arguing that it does not adequately reflect how strong Afghanistan's security forces have become. One American official, who described the NIE as "more dark" than past intelligence assessments on the war, said there are too many uncertainties to make an educated prediction on how the conflict will unfold between now and 2017, chief among them the outcome of next year's presidential election.

"I think what we're going to see is a recalibration of political power, territory, and that kind of thing," said one U.S. official who felt the assessment was unfairly negative. "It's not going to be an inevitable rise of the Taliban."

A senior administration official said that the intelligence community has long underestimated Afghan security forces.

"An assessment that says things are going to be gloomy no matter what you do, that you're just delaying the inevitable, that's just a view," said the official. "I would not think it would be the determining view."

U.S. intelligence analysts did not provide a detailed mapping of areas they believe are likely to become controlled by specific groups or warlords in coming years, said one of the officials. But the analysts anticipate the central government in Kabul is all but certain to become increasingly irrelevant as it loses "purchase" over parts of the country, the official said.

Some have interpreted the intelligence assessment as an implicit indictment of the 2009 troop surge, which President Obama authorized under heavy pressure from the U.S. military in a bid to strengthen Afghan institutions and weaken the insurgency. The senior administration official said the surge enabled the development of a credible and increasingly proficient Afghan army and made it unlikely that al-Qaeda could reestablish a foothold in the country where the Sept. 11 attacks were plotted.

"By no means has the surge defeated the Taliban," the official said, but its stated goal was to "reverse the Taliban's momentum and give the government more of an edge. I think we achieved that."

A spokesman for the Office of the Director of National Intelligence, which issues intelligence estimates, declined to comment. Officials at the White House declined to speak about the NIE's findings. In an e-mailed statement, a senior administration official said intelligence assessments are "only one tool in our policy analysis toolbox."

"One of the Intelligence Community's principal duties is to warn about potential upsides and downsides to U.S. policy, and we frequently use their assessments to identify vulnerabilities and take steps to correct them," the statement said. "We will be weighing inputs from the [intelligence community] alongside those of the military, our diplomats and development experts as we look at the consequential decisions ahead of us, including making a decision on whether to leave troops in Afghanistan after the end of 2014."

The Obama administration has sought to get permission from Kabul to keep troops that would carry out counterterrorism and training missions beyond 2014. Afghan President Hamid Karzai has so far refused to sign a bilateral security agreement with the United States. Karzai's intransigence has emboldened those in the administration and Congress who favor a quick drawdown.