WASHINGTON, July 17 — President Bush’s top counterterrorism advisers acknowledged Tuesday that the strategy for fighting Osama bin Laden’s leadership of Al Qaeda in Pakistan had failed, as the White House released a grim new intelligence assessment that has forced the administration to consider more aggressive measures inside Pakistan.

The intelligence report, the most formal assessment since the Sept. 11 attacks about the terrorist threat facing the United States, concludes that the United States is losing ground on a number of fronts in the fight against Al Qaeda, and describes the terrorist organization as having significantly strengthened over the past two years.

In identifying the main reasons for Al Qaeda’s resurgence, intelligence officials and White House aides pointed the finger squarely at a hands-off approach toward the tribal areas by Pakistan’s president, Gen. Pervez Musharraf, who last year brokered a cease-fire with tribal leaders in an attempt to drain support for Islamic extremism in the region.

“It hasn’t worked for Pakistan,” said Frances Fragos Townsend, who heads the Homeland Security Council at the White House. “It hasn’t worked for the United States.”

While Bush administration officials had reluctantly endorsed the cease-fire as part of their effort to prop up the Pakistani leader, they expressed relief on Tuesday that General Musharraf may have to abandon that approach, because the accord seems to have unraveled.

But American officials make little secret of their skepticism that General Musharraf has the capability to be effective in the mountainous territory along the Afghan border, where his troops have been bloodied before by a mix of Qaeda leaders and tribes that view the territory as their own, not part of Pakistan.

“We’ve seen in the past that he’s sent people in and they get wiped out,” said one senior official involved in the internal debate. “You can tell from the language today that we take the threat from the tribal areas incredibly seriously. It has to be dealt with. If he can deal with it, amen. But if he can’t, he’s got to build and borrow the capability.”

The bleak intelligence assessment was made public in the middle of a bitter Congressional debate about the future of American policy in Iraq. White House officials said it bolstered the Bush administration’s argument that Iraq was the “central front” in the war on terror, because that was where Qaeda operatives were directly attacking American forces.

The report nevertheless left the White House fending off accusations that it had been distracted by the war in Iraq and that the deals it had made with President Musharraf had resulted in lost time and lost ground.

While the assessment described the Qaeda branch in Iraq as the “most visible and capable affiliate” of the terror organization, intelligence officials noted that the operatives in Iraq remained focused on attacking targets inside that country’s borders, not those on American or European soil.

In weighing how to deal with the Qaeda threat in Pakistan, American officials have been meeting in recent weeks to discuss what some said was emerging as an aggressive new strategy, one that would include both public and covert elements. They said there was growing concern that pinprick attacks on Qaeda targets were not enough, but also said some new American measures might have to remain secret to avoid embarrassing General Musharraf.

Ms. Townsend declined to describe what may be alternative strategies for dealing with the Qaeda threat in Pakistan, but acknowledged frustration that Al Qaeda had succeeding in rebuilding its infrastructure and its links to affiliates, while keeping Mr. bin Laden and his top lieutenants alive for nearly six years since the Sept. 11 attacks.

The intelligence report, known as a National Intelligence Estimate, represents the consensus view of all 16 agencies that make up the American intelligence community. The report concluded that the United States would face a “persistent and evolving terrorist threat over the next three years.”

That judgment was not based on any specific intelligence about an impending attack on American soil, government officials said. Only two pages of “key judgments” from the report were made public; the rest of the document remained classified.

Besides the discussion of Al Qaeda, the report cited the possibility that the militant Lebanese group Hezbollah, a Shiite organization, might be more inclined to strike at the United States should the group come to believe that the United States posed a direct threat either to the group or the government of Iran, its primary benefactor.

At the White House, Ms. Townsend found herself in the uncomfortable position of explaining why American military action was focused in Iraq when the report concluded that main threat of terror attacks that could be carried out in the United States emanated from the tribal areas of Pakistan.

She argued that it is Mr. bin Laden, as well as the White House, who regarded “Iraq as the central front in the war on terror.”

Richard A. Boucher, the assistant secretary of state, acknowledged that Al Qaeda had prospered during the cease-fire between the tribal leaders and General Musharraf last September, a period in which “they were able to operate, meet, plan, recruit, and obtain financing in more comfort in the tribal areas than previously.”

But Mr. Boucher also described General Musharraf as America’s best bet, and several administration officials on Tuesday cited his recent aggressive actions against Islamic militants at a mosque in Islamabad.

The growing Qaeda threat in Pakistan has prompted repeated trips to Islamabad by senior administration officials to lean on officials there and calls by lawmakers to make American aid to Pakistan contingent on a sustained counterterrorism effort by General Musharraf’s government.

Some members of Congress argue that concern for the stability of General Musharraf’s government had for too long dominated the White House strategy for dealing with Pakistan, thwarting American counterterrorism efforts.

“We have to change policy,” said Representative Mike Rogers of Michigan, a Republican member of the House Intelligence Committee who has long advocated a more aggressive American intelligence campaign in Pakistan.

In an interview on Tuesday, the New York Police commissioner, Raymond W. Kelly, called the report a “realistic and sobering assessment,” but said it had not caused officials in New York to take any specific steps to tighten security in the city.

“There is no surprise here for us,” he said. “Would we rather it be another way? Yes. But this is the world, as it is, and this is what we are guarding against.”