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.