Some of the issues in the final discussion I tried to address in a story for TIME earlier this month, so rather than rewriting that story I'm pasting it in below:

Does Osama bin Laden matter anymore? You could be forgiven for thinking he doesn't. In recent months, an impressive cast of terrorism experts and counterterrorism officials around the world has coalesced around the notion that al-Qaeda's leader is no longer an active threat to the West. They point out that he has not been able to strike on U.S. soil since 9/11 or in Europe since the London bombings three summers ago. In Iraq, his most successful franchise operation is on the ropes. Across the Muslim world, opinion polls suggest his popularity has faded, and many of his early supporters -- including prominent jihadi ideologues -- have denounced him. Even his messages on the Internet scarcely merit headlines in the mainstream media. Did you know he posted two audio messages on the Web in May? I didn't think so.
<!--break-->The jihad, some experts contend, has moved beyond bin Laden and al-Qaeda. Dr. Marc Sageman, a former CIA case officer, lays out the view in his new book, Leaderless Jihad, arguing that "the present threat has evolved from a structured group of al-Qaeda masterminds controlling vast resources and issuing commands to a multitude of info rmal groups trying to emulate their predecessors by conceiving and executing operations from the bottom up. These 'homegrown' wannabes form a scattered global network, a leaderless jihad." According to this assessment, two decades since its founding in Peshawar, Pakistan, al-Qaeda remains a source of inspiration for certain extremists around the world. But it's far from clear that bin Laden commands them.

This view was shared by several European officials I met at a conference of terrorism experts in Florence in May, a few days after bin Laden's most recent Internet postings. The officials told me they've found no evidence of al-Qaeda operations in their countries. If bin Laden has any role in the jihad, say the Europeans, it is merely as an icon. Alain Grignard, Belgium's top terrorism investigator, says bin Laden is now a "Robin Hood figure; 100 people are inspired by him, but very few respond to do what he wants."

If that's true, why do so many political leaders continue to warn about the threat -- or even the likelihood -- of another major terrorist attack? Why did the U.S. National Intelligence Estimate say al-Qaeda "has protected or regenerated key elements of homeland attack capability"? Why would the head of Britain's domestic intelligence service, MI5, say there were 2,000 citizens and other U.K. residents who posed a serious threat to security, a number of whom took direction from al-Qaeda? The struggle against al Qaeda -- and to a lesser extent, the quest to capture bin Laden -- has20dominated U.S. foreign policy since 9/11.

But as the U.S. prepares to elect a new President, should that remain the case? The answers to these questions don't lend themselves to easy policy prescriptions. But the best available evidence suggests that the threat posed by bin Laden's acolytes hasn't been extinguished-- and his own influence over them is greater than many analysts acknowledge. In his old stomping grounds, the jihad is stronger than at any time since he fled from the Tora Bora mountains in the winter of 2001. The Taliban is resurgent in Afghanistan, and in Pakistan militant groups have grown so aggressive that in late June they even threatened to take over a major city -- Peshawar, once bin Laden's home and the birthplace of al-Qaeda. Farther away, extremists in Europe and North Africa continue to covet bin Laden's blessing and the al-Qaeda brand name.

As has always been true in shadowy, borderless wars, measuring the strength of the enemy isn't an exact science. It's true that many of the "leaderless jihadis" have set up operations independently of al-Qaeda, but when they turn to bin Laden's organization, it's not just for inspiration but also for training, assistance and direction -- in short, for leadership. Many are able and willing to do bin Laden's bidding; they pay very careful attention to his Internet postings and follow his instructions. And although their targets have generally been close to home, their association with al-Qaeda has tended to take their ambitions beyond their borders.

What's more, many of these homegrown wannabes live in the West. It was al-Qaeda's direct involvement that helped a leaderless group of British jihadis mount the multiple London bombings on July 7, 2005, that killed 52 commuters. Two of the bombers had traveled to Pakistan, met with al-Qaeda commanders and made martyrdom tapes with al-Qaeda's video- production arm there. A year later, British investigators uncovered a plot by another cell of British Pakistanis to bring down seven American and Canadian passenger jets. According to Lieut. General Michael Maples, head of the U.S. Defense Intelligence Agency, the plotters received direction from al-Qaeda in Pakistan.

Bin Laden's interest in British jihadis didn't end there. Jonathan Evans, head of MI5, said last year that "over the past five years, much of the command, control and inspiration for attack-planning in the U.K. has derived from al-Qaeda's remaining core leadership in the tribal areas of Pakistan." U.S. officials, too, worry that a new generation of jihadis is making the trek to Pakistan, seeking al-Qaeda's assistance. Sixteen U.S. intelligence agencies signed off on a 2007 National Intelligence Estimate that concluded that al-Qaeda has made a strong comeback in Afghanistan and Pakistan because it has found "a safe haven in the Federally Administered Tribal Areas [FATA] in Pakistan" for its operational lieutenants and top leadership. In February, Michael McConnell, director of National Intelligence, said in congressional testimony that there had bee n an "influx of new Western recruits into the tribal areas since mid-2006." Philip Mudd, the former No. 2 in the CIA's Counterterrorism Center, who is now working at the FBI to help improve its intelligence capabilities, told me, "There is a very clear, almost mathematical increase in lethality as soon as plotters touch the FATA."

If jihadis seek material assistance from al-Qaeda in the FATA, they can get guidance from bin Laden almost anywhere there's an Internet connection. He has issued more than two dozen video- and audiotaped messages since 9/11, and some of his exhortations have been acted upon. For instance, in December 2004, bin Laden called for attacks on Saudi oil facilities; in February 2006, al-Qaeda in Saudi Arabia attacked the Abqaiq facility, perhaps the most important oil-production facility in the world. (Luckily, that attack was a failure.) More recently, bin Laden has called for attacks on the Pakistani state -- there were more than 50 suicide bombings there in 2007, and there have been at least 19 thus far this year.

There's some comfort to be drawn from the fact that bin Laden has not been able to strike on U.S. soil since 9/11. There is scant evidence of al-Qaeda sleeper cells in the U.S. Thanks to more effective intelligence-gathering, immigration control and the heightened vigilance of ordinary Americans, it is very hard for terrorists to slip into the country. It's always possible that homegrown wannabes will mount some sort of attack, but in contrast to the situation in Europe, al-Qaeda's virulent ideology has found few takers in the American Muslim community.

Yet bin Laden remains determined to kill large numbers of Westerners and disrupt the global economy. Since 9/11, al-Qaeda and its affiliates have bombed Western-owned hotels around the Muslim world, attacked a number of Jewish targets and conducted suicide operations against oil facilities in the Middle East; we can expect more of the same in the future. Al-Qaeda has also used new tactics and weapons -- like the surface-to-air missile that nearly brought down an Israeli airliner in Kenya in 2002. And it retains a long-standing desire to acquire a radiological bomb. But al-Qaeda's most dangerous weapon has always been unpredictability. That's why it is dangerous to dismiss bin Laden as a spent force. While he remains at large, the jihad will never be leaderless.

The either-or nature of the question misses the point. The reality is that we face BOTH a decentralized Al Qaeda manifested by self-radicalized or homegrown "bunches of guys" for whom the al Qaeda name is just a brand or symbol AND a centralized, core al Qaeda group which is still plotting and planning attacks from the Afghan/Pakistan frontier.

<!--break-->As I noted earlier in this discussion thread, the threat today comes from al Qaeda core, al Qaeda affiliates, and local cells. There is much to be said of both Sageman and Hoffman's analyses, but the assumption that the core al Qaeda threat is behind us is simply belied by everything we hear from the intelligence and law enforcement communities. Recognizing the evolution toward a core group that functions as a type of symbolic leadership for a broad and decentralized movement is equally important. To date there is still no clear link between the Madrid bombers and the al Qaeda core. The link between al Qaeda and the London bombers, however, is pretty clear.

But it is also true that part of the successful evolutionary change within al Qaeda has been due to its resilience. Each time we take out an al Qaeda military commnander (Khalid Sheik Mohammed, al-Libbi, Hamza al-Ribai...) another comes along. These terrorist tacticians, however, are far more important today than Bin Laden himself. Even within the al Qaeda core leadership, it is Ayman al-Zawahiri who is the brains behind the group, as is especially evident looking at the group's media and propaganda efforts. Capturing or killing Bin Laden would be a major psychological blow to al Qaeda (and perhaps more so to the local and independent but like-minded fellow travelers), and it would be a significant accomplishment and morale booster for the Western coalition, but it would do nothing to actually harm, diminish the capabilities of or undercut support for al Qaeda. Al Qaeda today has outgrown Bin Laden.

Gregory offers a thoughtful analysis and has bravely baited the rest of us to respond, so I'll take the bait. First, and just FYI, my "not unrelated" comment was intended to link energy and the economy, not the economy and terrorism.<!--break-->That said, there is an interesting side note to add here, though it only underlines to my mind how the recent economic downturn in particular and economics in general is mostly unrelated to efforts to combat terrorism (the exception, of course, is the tremendous costs of fighting two wars, especially the war in Iraq, which was never truly part of the poorly phrased war on terror). That is, al Qaeda has been extremely effective at conducting economic warfare -- al Qaeda has expended relatively little treasure to inflict on the U.S. and the West in general exorbitant costs. Look to senior al Qaeda leaders' statements to underscore that this is part of their strategy. Consider also the recent case in Canada involving Monin Khawaja, who reportedly wrote in a 2003 email, "So we have to come up with a way that we can drain their economy of all its resources, cripple their industries, and bankrupt their systems in place, all so that they are forced to withdraw their troops, so they cannot afford to go to war.... We need constant economic j[ihad], blow after blow, until they cripple and fall, never to rise again." In that, despite the costs we have incurred (some unnecessarily), I submit that have and will continue to fail - but there is that connection in terms of their intent.

Gregory agrees that terrorism "is very important indeed and requires continued
maximal vigilance and sustained attention." So the fact that al Qaeda has failed to conquer territory, while telling and a sign of its inherent bankrupt ideology, really doesn't mitigate the threat it poses to America and its allies. And taking our allies into account is critical. Al Qaeda affiliates in North Africa, for example, may pose less of a threat to the U.S. but it is the primary threat facing our allies in much of Europe, particularly France, Spain and Italy. Giving our transatlantic relationships greater attention is not well-served by playing down the threats posed by al Qaeda's regional affiliates. And as to the homegrown threat, the New York Police Department's http://www.nypdshield.org/public/SiteFiles/documents/NYPD_Report-Radical... ">study should be a wake-up call to us all -- the radicalization Peter and I have discussed in the UK context may well be happening in parts of the United States as well.

Gregory and I apparently disagree over the seriousness of the threat posed by Iran -- that's an important debate but a different one that the one we're having now so I'll leave that for another time. But should terrorism continue to be the - or one of the - "premier national security priorities" of the next administration (the questions we've been asked to address here)? Yes. Gregory's musing whether it is also the "defining challenge of the 21st Century" is in fact a totally different question. I submit that if we give the issue the attention it needs now there is no reason it should be "the defining issue" when historians later look back at the 21st Century.

Finally, Gregory makes an important point when he highlights the growing importance of Russia, China, and India, among other states, to which we need to give greater attention. The next administration will need to walk and chew gum at the same time, focusing on counterterrorism while balancing not only other priority issues and countries but even sometimes competing foreign policy interests, as we've discussed earlier regarding, for example, the democracy agenda, Arab reform, combating AIDS/HIV in Africa, etc. We'll need to deal with all these critical issues, and fix the economy and the housing market and plenty of other things at home, but combating terrorism will remain a priority for at least the next four years, so yes: it deserves to be at the very top of the next administration's priority list.

I agree with Matt Levitt and others that tackling the threat of Al Qaeda terrorism should remain a top-tier national security priority. In the coming decades more significant challenges will no doubt emerge, most important of which will be managing the rise of China. And in the nearer term the Iran nuclear standoff will continue to loom large.<!--break-->But Al Qaeda, impossible to deter like Iran, should still top the next President's national security briefings. As others have pointed out, Al Qaeda has regenerated its ability to attack the United States from its training camps in Pakistan. There was no greater demonstration of this than a plot thwarted here in London in August 2006 to bring down up to seven commercial airliners en route to North America. The trial, which I've been attending, has revealed that the alleged plotters were trained in Pakistan in how to make explosive devices, and had assembled all the materials necessary to manufacture bombs that would have been undetectable by airport security.

British officials believe the plan may have been to explode the planes over American cities. Seven 'Lockerbie' type events over New York, Washington DC, San Francisco, Chicago and other densely populated North American metropolises would likely have produced a death toll larger than 9/11. If the plot had been successful, one can only imagine the impact it would have had on the global aviation industry, the U.S. economy, and the international financial system.

Unfortunately as long as Al Qaeda is able to train recruits with relative impunity in north-western Pakistan, it will remain a strategic threat to the United States.

New airport security regulations have made launching an attack on airliners more difficult, but there are still a range of attack scenarios that could cause significant damage the United States. While it is extremely unlikely that Al Qaeda could get hold of a nuclear weapon, it may more realistically be able to deploy a radiological device (or 'dirty bomb') in a U.S. city. Although such a device (essentially conventional explosives packed with radioactive materials) would cause less fatalities than sometimes speculated - with the danger to public health limited to about a city block -it could create tremendous public fear.

The next U.S administration should not, therefore, downgrade tackling the Al Qaeda terrorist threat as a national security priority. But resources should certainly be better allocated. Money spent on improving intelligence and law enforcement capabilities delivers much greater security gains per dollar than money lavished on border security fences or expensive scanners to screen container shipments for radioactive devices. That is not to say that resources should not be allocated to such defenses but given the dozens of ways Al Qaeda could get round them, the United States should steer clear of a Maginot mentality. As the title of a new book by former NYPD Counter-terrorism Commissioner http://www.amazon.com/Crush-Cell-Terrorism-Terrorizing-Ourselves/dp/0307...
">Michael Sheehan makes clear, the priority should always be to 'Crush the Cell.'

Will Al Qaeda's still be the top national security priority in a decade? Much will depend on whether the Pakistani government wakes up to the threat posed by Al Qaeda in the tribal areas of the country. But there are some grounds for believing that Al Qaeda will be a lesser force in ten years. As Peter Bergen and I www.tnr.com/politics/story.html?id=702bf6d5-a37a-4e3e-a491-fd72bf6a9da1
">reported recently in the New Republic, there is an emerging backlash against Al Qaeda in Muslim countries, a function of it killing so many Muslims in recent years and so nakedly targeting western civilians.

A pattern has emerged, most visibly in Iraq but also now in the Northwest Frontier Province of Pakistan, that when Al Qaeda's brand of violence comes to people's doorsteps, sympathy for the terrorists dramatically decreases. Furthermore, leading Jihadists, with clout amongst Al Qaeda's target audience of radical-leaning youngsters, have started to publicly articulate the differences between 'legitimate' Jihad and Al Qaeda's campaign of terrorism.

The fact that Al Qaeda may be starting to self-implode has, I think, some implications for the second discussion prompt on the degree to which the U.S. military should be employed in combating terrorism. While given the current local dynamics, there are strong arguments for boosting U.S. troop levels in Afghanistan, and maintaining a residual number of troops in Iraq, there should be strong restraint in deploying the military in other arenas. The last thing the United States should grant Al Qaeda, when it is facing so much criticism from within the Jihadist movement, is another 'cause celebre.' Without the recruiting boost provided by the U.S. invasion of Iraq in 2003, Al Qaeda, an organization on the ropes in 2002, would have been significantly less of a threat than it is today.