The pattern of terror strikes we've seen since 9/11 is back to being very similar to the pattern we endured in the 1970s and early 1980s: they can blow things up in their own neighborhood (Middle East), and on occasion, they can reach into the areas surrounding their own—but no farther.
I think this is false, and I further suspect that it will be a very dark day indeed when we discover just how false it is. I think this belief is false because it constitutes a pretty serious overestimation of Al Qaeda's overall abilities.
The general refrain is this: "If Al Qaeda could attack us, they would. They haven't; ergo, they are currently unable to attack us." This is then attributed to the War on Terror, and I'll certainly grant that we have probably managed to provide Al Qaeda with some serious disruption of its mechanisms. So what's my problem with the above?
Simply put, Al Qaeda has been around for something like fifteen years, and in all that time, it has only been able to launch two major attacks in the United States. That's it: two. The World Trade Center bombing in 1993, and the attacks on 9-11. I have read further reports (though I don't recall where, so I can't link them, but I'll try to find something later) that A-Q actually came close to calling off the 9-11 plot. In any case, as bad as 9-11 was, it didn't do nearly as much damage as it could have*. (Imagine if the hijackers had taken over planes an hour or two later, when -- an hour or two into the work day, as opposed to at the very beginning of it -- there would have been far more people in the Twin Towers than there were at 8:45 in the morning when the first plane hit.) The 9-11-01 attacks took years for Al Qaeda to implement, as crazy as that sounds, since the general scheme isn't that complex. Face it: as a bit of strategy, "Hijack a couple of planes and crash them into downtown NYC" isn't exactly a scheme of Blofeldian complexity.
It seems to me that Al Qaeda has never really had that much ability to make major strikes of the 9-11-01 variety, which is why they've only managed to pull off exactly one such strike (anywhere, and not just here). Sure, they've car-bombed embassies, and they put a big hole in the USS Cole; and let's not trivialize what they wrought in Bali and in Madrid and the fact that they are commonly accepted to be connected with the terrorists in Russia who launch fairly frequent attacks in that country. But the fact is this: the smaller-scale (but still awfully bloody) attack has always been the stock-in-trade of Al Qaeda and similar organizations. We should not assume that the 9-11-01 attacks heralded some kind of newfound ability to execute spectacular attacks, and therefore conclude that our efforts since then have neutered this newfound ability. After 9-11, everyone thought that more attacks were on the way, but that doesn't mean that they were.
I guess that's the big problem with a conceptual war like the War on Terror: it's well-nigh impossible to come up with a metric for victory that's really convincing. I'd like to believe that we've seriously dealt Al Qaeda a series of blows, and for all I know, we have. But I don't think that the absence of 9-11-01-style attacks points to a loss of Al Qaeda's very ability to pull off 9-11-01-style attacks.
* A scenario that sometimes wakes me up at night is if the 2001 plot hadn't been a 9-11 plot, but a 9-09 plot. September 9, 2001 was the opening day of the NFL regular season. Imagine the carnage if four jumbo jets had slammed into sold-out NFL stadiums.