Al-Qaeda's new strategy....

More Mumbai style-attacks...

The scene in Europe last week called to mind the heyday of the IRA in the 1970s or of Algerian terrorism in the 1990s: Buckingham Palace and Trafalgar Square were teeming with police, the Eiffel Tower was repeatedly evacuated, and everywhere, tourists were on edge. The threat, however, involved a newer brand of terrorist: The CIA and its European counterparts warned of an al-Qaeda plot to kill civilians in France, Germany and Britain, and alerted travelers, especially Americans, to be extra-vigilant.

Few operational details were released. But unlike many thwarted al-Qaeda operations of days gone by -- such as the 2006 Heathrow plot, in which several airliners bound from London to America were to be blown up at coordinated intervals -- it was clear from news reports that the European plan called for less spectacular, smaller-scale attacks, perhaps using machine guns to strafe clusters of tourists near public landmarks.

Has al-Qaeda become dispirited? No.

Recent plots, including the Mumbai raid in November 2008, the Times Square car bomb attempt in May of this year and now the plot in Europe, show that al-Qaeda is not only operationally alive and well, but has transformed its post-Afghanistan tactical retreat into a formidable new strategy. In the early part of the last decade, al-Qaeda had no choice but to use conventional explosives and old-fashioned terrorist tactics to hit soft targets, the 2002 bombing of nightclubs in Bali being perhaps the best example. With its leadership under siege in Pakistan, it lacked the capacity to mount sophisticated and coordinated attacks that would match, let alone exceed, the innovation or shock value on display on Sept. 11, 2001, or even in the USS Cole operation the year before.

Watching this shift, the tacit assumption of most counterterrorism officials and analysts was that al-Qaeda was simply biding its time and trying to rebuild its capacity to stage unprecedented, apocalyptic attacks on the United States and Europe. But even if that was once the group's intention, it appears to have been sidelined.

The new al-Qaeda seems to understand its limitations and appears to be adopting more realistic means of achieving its grand objectives. There is no reason to think that al-Qaeda has abandoned its all-out jihad to defend Islam against what it sees as centuries of repression and humiliation at the hands of the West. But instead of fomenting revolutionary outrage with spectacular gestures, it is slowly raising a new army designed to wage traditional urban warfare.

Some members of this second-generation army have been seasoned by the classical insurgencies in Iraq and Afghanistan; others are Western members of the Muslim diaspora or converts to Islam. Although many of them have attended al-Qaeda training camps, a large number of them lack traditional terrorist pedigrees and have no criminal records.

With the help of these so-called "cleanskins," who are difficult for Western security services to detect, al-Qaeda's opportunistic, pragmatic leadership has embraced urban warfare of the sort pioneered by terrorists decades ago: low-intensity, IRA-style operations in densely populated areas, using both conventional military weapons (such as assault rifles and rocket-propelled grenades) and standard terrorist weapons (such as improvised explosive devices). This, not simultaneously blowing up airliners or destroying skyscrapers, was the mode of jihad envisioned by Abd al-Aziz al-Muqrin, the late leader of the jihad in Saudi Arabia and the author of the appropriately named turn-of-the-century al-Qaeda combat manual "The War Against Cities."

This vision of a close-quarters confrontation with the general population is at least as disconcerting as the more novel style of apocalyptic terrorism that the strikes against the Pentagon and the World Trade Center appeared to herald. For one thing, it could eventually bring about an ongoing, direct, ground-level armed engagement of Western security forces -- think of Belfast or Beirut in the 1970s and 1980s. That sort of campaign could ultimately shake the public's confidence in the state to a greater extent than have less frequent, larger-scale operations such as the 9/11 attacks.