Today the U.S. military and NATO are engaged with the Taliban on a scale not seen since the winter of 2001, both because coalition forces are pushing into areas that were formerly no-go and dominated by the Taliban, and because religious warriors have regrouped substantially over the past few years. In the past three months, U.S. military officials estimate that coalition forces have killed more than a thousand Taliban, while the religious militia has in turn killed dozens of coalition soldiers and hundreds of ordinary Afghans, creating a climate of fear in much of the country.

The key to the resurgence of the Taliban can be summarized in one word: Pakistan. The Pakistani government has proved unwilling or incapable (perhaps both) of clamping down on the Taliban. Unless that changes, Afghanistan will be plagued by instability for years to come.

To the extent that Al Qaeda has a new base it is in Pakistan. From there Al Qaeda’s leaders, Osama bin Laden and Ayman al-Zawahiri, have released a stream of audio and videotapes -- 18 so far this year alone -- that pump up their base and incite violence against Westerners, Americans, and Jews.

Al Qaeda has also succeeded in reconstituting itself to some degree on the Afghan-Pakistan border. Evidence can be seen in the advice, assistance, and personnel Al Qaeda is offering the Taliban in its campaign of suicide attacks in Afghanistan, as well as in the London bombings of July 7, 2005. The two lead suicide bombers in the London attacks recorded suicide "wills" with Al Qaeda’s video production arm, As-Sahab, and received bomb-making training in Pakistan, according to British officials.

Al Qaeda has also been able to deepen its cooperation with Kashmiri militant groups such as Lashkar-e-Toiba and Jaish-e-Mohammed -- for example, sharing training facilities and safe houses. The Kashmiri issue is also being mobilized by Al Qaeda in Pakistan to bring in recruits.

The fact that Pakistan is the new training ground for Al Qaeda recruits is deeply worrisome and indicates that Al Qaeda "the organization" will continue to be a significant threat. Terrorist plots have a much higher degree of success if some of the cell’s members have received training in bomb making and operational doctrine.

The 11 people charged in August with conspiring to blow up planes using liquid explosives are all British citizens. So were the terrorists who attacked London in 2005, almost all of the plotters who allegedly conspired to detonate a fertilizer bomb in England in 2004, the suicide bombers who attacked a beachfront Tel Aviv bar in 2003, and an alleged Al Qaeda operative who, along with would-be shoe bomber Richard Reid, planned to explode a plane in the fall of 2001.

For terrorist organizations like Al Qaeda, ethnic Pakistanis living in Britain make perfect recruits, since they speak English and can travel on British passports. Indeed, in the wake of August’s high-profile arrests, it can now be argued that the biggest terrorist threat to U.S. security emanates not from Iran or Iraq or Afghanistan but rather from Britain, our closest ally.

Five years after the attacks on Washington and New York, we face a world of ideologically driven home-grown terrorists -- free radicals unattached to any formal organization -- in addition to formal networks such as Al Qaeda that have managed to survive despite the tremendous pressure brought to bear against them since 9/11. And they now feed off and strengthen one another.