WASHINGTON, July 17 — Nearly six years after the Sept. 11 attacks, the hundreds of billions of dollars and thousands of lives expended in the name of the war on terror pose a single, insistent question: Are we safer?

On Tuesday, in a dark and strikingly candid two pages, the nation’s intelligence agencies offered an implicit answer, and it was not encouraging. In many respects, the National Intelligence Estimate suggests, the threat of terrorist violence against the United States is growing worse, fueled by the Iraq war and spreading Islamic extremism.

The conclusions were not new, echoing the private comments of government officials and independent experts for many months. But the stark declassified summary contrasted sharply with the more positive emphasis of President Bush and his top aides for years: that two-thirds of Al Qaeda’s leadership had been killed or captured; that the Iraq invasion would reduce the terrorist menace; and that the United States had its enemies “on the run,” as Mr. Bush has frequently put it.

After years of war in Afghanistan and Iraq and targeted killings in Yemen, Pakistan and elsewhere, the major threat to the United States has the same name and the same basic look as in 2001: Al Qaeda, led by Osama bin Laden and Ayman al-Zawahri, plotting attacks from mountain hide-outs near the Afghan-Pakistani border.

The headline on the intelligence estimate, said Daniel L. Byman, a former intelligence officer and the director of the Center for Peace and Security Studies at Georgetown University, might just as well have been the same as on the now famous presidential brief of Aug. 6, 2001: “Bin Laden Determined to Strike in U.S.”

The new estimate does cite some gains; known plots against the United States have been disrupted, it says, thanks to increased vigilance and countermeasures.

But the new estimate takes note of sources of worry that have arisen only since 2001. The Iraq war has spawned Al Qaeda in Mesopotamia as the “most visible and capable affiliate” of the original terrorist group, inspiring jihadists around the world and drawing money and recruits to their cause. The explosion of radical Internet sites has created self-generating cells of would-be terrorists in many Western countries. Lebanese Hezbollah, rarely considered likely to attack in the United States, now “may be more likely to consider” doing just that in response to a perceived threat from American forces to itself or its sponsor, Iran.

And if there had been progress after 9/11 in isolating and immobilizing Al Qaeda’s leaders in the tribal areas of Pakistan, some of it has come apart in the past year, with Pakistani troops abandoning patrols in North Waziristan and allowing greater freedom of movement to Al Qaeda’s core.

All told, despite the absence of any new attack on American soil since 2001, the conclusion that Al Qaeda “will continue to enhance its capabilities” to attack the United States suggests some miscalculation in the administration’s basic formula against terrorism: that attacking the jihadists overseas would protect the homeland.

“I guess we have to fight them over here even though we’re fighting them over there,” said Steven Simon, a terrorism expert who served in the Clinton administration and is the co-author of “The Next Attack.”

Democrats proclaimed the document a “devastating indictment” of Bush administration policies, in the words of Senator Joseph R. Biden Jr., the Democratic chairman of the Foreign Relations Committee and a presidential candidate. The document’s pessimism was striking; it may reflect a determination of the intelligence agencies, accused of skewing some reports to back the president’s Iraq invasion plans in 2003, to make clear that their findings have not been tailored to suit the White House this time around.

But Max Boot, a security analyst who has generally supported the president, said the estimate “cuts both ways” politically. Even if some administration policies have been ineffective or have backfired, the estimate also concludes that Al Qaeda will likely try to capitalize on the network built up by its affiliate in Iraq, lending some support to the argument that a rapid exit from Iraq might prove dangerous for American security, said Mr. Boot, a senior fellow at the Council on Foreign Relations and the author of “War Made New.”

“It makes clear that the threat from Al Qaeda in Iraq is not just to Iraqis — it’s to the U.S. homeland as well,” Mr. Boot said.

The new assessment in some respects harks back to a National Intelligence Estimate in July 1995, which predicted terrorist attacks in the United States, specifying Wall Street, the White House and the Capitol as potential targets. It described “a worldwide network of training facilities and safe havens.”

An update of that N.I.E. in 1997 was the last such assessment issued before Sept. 11, a gap that the 9/11 commission decried in its review of the attacks. A new estimate earlier in 2001, as the spy agencies’ alarm about a possible attack increased, might have better focused government efforts to detect a plot, the commission argued in its report.

An estimate of the global terrorist threat last September described the emergence of the Iraq war as a “cause célèbre” for jihadists around the world. But that document also highlighted American actions it said had “seriously damaged the leadership of Al Qaeda and disrupted its operations.”

The bleak new assessment relegates almost to an aside those achievements, saying that Al Qaeda’s ability to attack is “constrained” and that the United States is now seen as a “harder target.” And it does not emphasize the absence of successful new strikes against the United States, a development that few security experts would have dared predict in late 2001.

The dreary judgment reflected in the new estimate emerged in part from Britain’s discovery in August 2006 of a major plot to take down trans-Atlantic airliners, said Bruce Hoffman of Georgetown University, who had studied terrorism for three decades. Mr. Hoffman said that there were indications that Al Qaeda leaders may have had a role in the plot, adding, “It became impossible to ignore Al Qaeda’s evolution and resilience.”

But the same plot underscored one of the notable bright spots for the United States: jihadist sentiment has so far turned out to hold little attraction for American Muslims, by contrast with those in Europe generally and the United Kingdom in particular, with its large population of South Asian immigrants.