WASHINGTON, 12 September 2006 — Five years after Sept. 11, is the United States winning the war against Al-Qaida? In a series of recent speeches to mark the anniversary of the attacks, President Bush has declared: “America is winning the war on terror,” and cited a list of achievements.

But terrorism experts worry that those successes have been mostly tactical, short-term gains. On longer-term strategic issues, they warn, the United States might have lost ground since 2001:

— Al-Qaida, the initial focus of the so-called “global war on terror,” has been disrupted and dispersed. But it has been succeeded by a looser network of affiliates and homegrown terrorists — including those who carried out bombings in Madrid in 2004 and London in 2005 — who could grow to be just as dangerous.

— The war in Iraq has become a training ground for extremists from other countries, and some experts fear the Gulf’s oil terminals could be among their next targets.

— Wars in Iraq, Afghanistan and Lebanon have damaged the image of the United States in much of the Muslim world, and made it easier for terrorist organizations to win recruits. The wars and controversies over US treatment of detainees also have made it more difficult for allied governments to cooperate with American counterterrorism programs, diplomats say.

— When Foreign Policy magazine surveyed more than 100 experts earlier this year, 84 percent said they did not believe the United States was winning the war on terrorism. In a Los Angeles Times poll, fewer than one-quarter of Americans said they believe the nation is “winning”; more than half said it was too soon to tell.

At first glance, the experts’ gloom might seem odd. There haven’t been any successful terrorist attacks inside the United States since Sept. 11, although law enforcement officials say there have been several close calls.

“It’s been five years, and the US homeland has not been hit,” said Daniel Byman, director of Georgetown’s security studies program. “I don’t know any terrorism experts who called this. ...We were all wrong.”

As a result, he said: “My assessment is that we’re doing reasonably well. If the test is reducing catastrophic violence that can change our lives, we’re doing rather well. If it’s reducing the overall climate of violence, we’re doing fairly poorly. If 30 or 40 Americans die from terrorism each year, that’s a tragedy, but it’s different from losing 3,000 a year. It’s a problem, but it’s probably not a strategic problem.”

Indeed, some national security experts — including John Mueller of Ohio State University — argue that the terrorist threat has been overblown and that a “terrorist industry” of consultants, government contractors and politicians is hyping the problem out of self-interest. “For all the attention it evokes, terrorism, in reasonable context, actually causes rather little damage,” Mueller said, noting that automobile accidents kill many more Americans than terrorists do. “The likelihood that any individual will become a victim in most places is microscopic.” But the consensus of government officials and nongovernmental experts is that the terrorist threat remains real, and the respite from violence is temporary.

“Why have we not suffered (another) attack?” asked Lee H. Hamilton, co-chairman of the Sept. 11 Commission, which exhaustively studied the 2001 attacks. “The honest answer is: We don’t know. We simply don’t know. Because we don’t know the minds of the terrorists.”

Added Paul Pillar, a former top CIA analyst: “The line between an attack that occurs and one that doesn’t can be very thin. It comes down to luck and circumstance with regard to any particular operation.”

One theory on the lack of homegrown terrorism inside the United States — especially in contrast to Europe, where police have foiled several planned attacks — is that Muslims in this country are more assimilated and less alienated.

“There are a lot of possible explanations,” said Byman. “But they’re all conjecture.”

In any case, most Bush administration officials have been careful to avoid taking credit for the fact that there has been no second Sept. 11 attack — because, they say, they still expect one. “We have hurt Al-Qaeda severely, I think, but they continue to work toward another 9/11 or something even more spectacular,” said Crumpton.

Although there have been no other attacks inside the United States, terrorism as a worldwide phenomenon has not diminished since 2001. The National Memorial Institute for the Prevention of Terrorism, which maintains an exhaustive database, reports that terrorism has killed more than 2,300 people every year since 2001.

Most of those fatalities resulted from domestic terrorism — attacks that stemmed from strife within a single country — rather than international attacks such as Sept. 11. But the institute’s research director, James O. Ellis III, argues that domestic terrorism often gives birth to the international kind.

The number of deaths from terrorism in 2005 swelled to more than 8,000, mostly because of sectarian violence in Iraq. But even outside Iraq, 1,952 civilians died in terrorist attacks last year.

“In international terrorism, we’ve seen a decrease in the number of incidents but a rise in lethality; more people are dying,” Ellis said. “In domestic terrorism, we’ve seen a rising number of incidents and rising lethality too.” The statistics are part of a broad debate on how best to gauge progress in the larger battle — a measure the Pentagon calls “metrics.”

In October 2003, US Defense Secretary Donald H. Rumsfeld wrote a memo to his closest aides, asking: “Are we winning or losing the global war on terror?”

“Today, we lack metrics to know,” Rumsfeld complained. “Are we capturing, killing or deterring and dissuading more terrorists every day than the “madrasas” (Islamic religious schools) and the radical clerics are recruiting, training and deploying against us?”

He told his aides he wanted better measuring sticks and a clearer strategy.

Almost three years after Rumsfeld’s memo, the Bush administration last week issued a long-range plan, the “National Strategy for Combating Terrorism,” most of the details of which remain classified. But the Pentagon concluded it just wasn’t possible to keep accurate track of terrorist recruiting trends, as Rumsfeld had asked — especially as Al-Qaeda evolved from a close-knit organization into an amorphous, radical movement.