WASHINGTON -- The single most puzzling -- and arguably most important -- question of the day is the one no one raises in public: Why have we not been attacked again?
We are coming up on two and a half years since Sept. 11. Think back: on Sept. 11, everybody was waiting for the other shoe to drop -- within days or weeks, but surely within months. When nothing happened, it was said that al Qaeda works on 18-month cycles, with long planning and preparation.
Well, it is now almost a year plus 18 months. And while there have been terrorist attacks against generally soft targets in other (mostly Islamic) countries, we have not had a single attack, major or minor, in the United States.
It is easy to understand why nobody wants to talk about this. The administration dare not take credit for what is on the face of it an amazing phenomenon, but one that can reverse itself in a flash. And the opposition hardly wants to highlight a development that might shed favorable light on this administration's post-9/11 stewardship.
Even commentators are uneasy about bringing it up. Any analysis could instantaneously turn into embarrassment.
Nonetheless, it seems odd to have a moratorium on so intriguing a question. I ask it of almost every intelligence expert I meet. Their speculations fall along two lines.
The first is that al Qaeda has been so severely degraded and disrupted that it simply cannot do it. It has lost its Afghan base, lost much of its funding and is reduced to going back to where Islamic radicals were years ago: launching minor guerrilla operations in Pakistan/Afghanistan, and sending operatives out to hit soft targets such as synagogues in Tunisia and embassies in Istanbul.
A variation on this theme is the idea that as al Qaeda International shrinks, terrorism is becoming more regionalized, being taken over by actors such as Jemaah Islamiyah (Indonesia), Abu Sayyaf (Philippines) and Ansar al-Islam (Iraq).
That may not be a terribly good development for the world, but it would be an explanation for why America has not been attacked. If you are an Indonesian terrorist, your objective is to destroy your government and to take it over. Hitting the Vegas Strip -- no matter how spectacularly -- becomes a distraction.
But I remain puzzled. Let's say that al Qaeda is so badly hurt that it cannot organize another Sept. 11 with 19 hijackers, four planes and years of training. But how much training, how much planning can it take to pack a few truck bombs and blow them up in a bunch of crowded shopping malls? Considering the economic and psychological havoc that would wreak, why haven't they done it?
Charles Krauthammer is a 1987 Pulitzer Prize winner, 1984 National Magazine Award winner, and a columnist for The Washington Post since 1985.
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