And you could say the same for lots of conspiracy theories of the past. Take the "domino theory" -- that the North Vietnamese Communists were the spearhead of a grand plan of the Chinese and Russian leaderships combined to convert the entire Indo-Chinese peninsula to Communist rule. But the North Vietnamese government were fundamentally nationalist autocrats, with a little Communist veneer, who were actually playing China and Russia off against each other, and didn't have much interest in spreading Communism past their borders. The only other domino that fell was Cambodia, and that because we had destablized it with our own bombing campaigns. What's more, when the Khmer Rouge regime there got to be too much to take, it was the North Vietnamese who chased it out (and the U.S. actually supported the Khmer Rouge in the subsequent diplomatic byplay -- I never understood why, unless it was just spite). So we can now say for certain that that was a crock. But for years, people at the highest levels of our government believed it.
They believed it because it was, at least superficially, credible. It was credible because these things are sometimes true -- as in Iran-Contra, where we really did sell arms to the Iranians, violating our own declared embargo, in order to use the proceeds to fund guerillas trying to overthrow governments that a Republican administration didn't like in Central America, violating yet another ban on arms trafficing imposed by Congress. Or, even more to the point, the Communist plan to infiltrate spies into sensitive areas of our government (remember Klaus Fuchs?), and establish puppet regimes all over Europe (they'd already done it in the east).
So, let's consider the conspiracy now uppermost in the minds of Americans -- Osama bin Laden's conspiracy to topple governments throughout the Muslim world, and replace them with a caliphate which endorses more or less his own style of theocracy (of which the Afghan Taliban can be considered a kind of preview).
Now, it's an error to assume that all religious Muslim radicals are necessarily part of the same grand scheme -- the religious disputes between, say, the terrorist-sponsoring Shiite theocrats of Iran and the extreme Sunni leadership of al-Qaeda matter a great deal more to them than they do to us. However, you really can't understand what's going on in one local scene there without looking at action over the borders. Fighters are sometimes recruited in one place for action somewhere else (as when we recruited a certain young Saudi to help us kick Communists out of Afghanistan). And if nothing else, atrocities in one place may wind up being used as propaganda points elsewhere. Our current trouble in Fallujah, for instance, was apparently triggered, and almost certainly worsened, by Sharon's assassination of a Palestinian leader in the West Bank. (If you liked that, stay tuned. There may be more coming.)
Besides, radical Muslims of all stripes share certain interests
regardless of their own factional disputes -- which can be briefly
summarized as getting rid of us (and our friends, and our proxies).
So, even if it's oversimple to paint Osama as the sole radical Muslim
mastermind wanting to topple the relatively secular and U.S.-friendly
dominos governments now in power throughout much of
dar el-Islam, it's nevertheless the case that the establishment of a
radical regime, or a radical movement, in one place, may catalyse
action against another, in a different place.
So, taking the long view: the U.S. knocked over the secular power in Iraq. Our leaders, such as they are, plainly had the idea that they could replace it with the regime of their choice. Real life is more complicated. But Iraq per se is not hugely significant right now. Not nearly as significant in itself as what it may portend for other Muslim states of greater significance -- say, Saudi Arabia, or nuclear Pakistan.
Which leads to the truly crappy conclusion that we might have been better off leaving things be -- leaving the potentially noxious Saddam in power, on a leash, and leaving the civilians he oppressed, and the kids dying of preventable diseases because of our crackpot embargo on antibiotics, in the position of that kid in The Ones Who Walk Away From Omelas. There were, after all, worse places in the Muslim world, particularly for women. But I've been arguing that since before the war.
Advocates of the invasion, many of them, thought they had a better idea. But the people leading it rejected not only the plans which had been put together with great care by the State Department, but the whole process of planning. We will have to live with the result.
But we still have choices. And, unfortunately, the Americans broadcasting transparently phony whitewashes of the military action in Fallujah are choosing, by giving our enemies splendid propaganda, to make things worse -- in Iraq or elsewhere. (But they're only transparently phony to people on the scene; you wonder if their attention is more on voters in the U.S.)
More generally, a bad occupation hurts us -- more so, to be completely cold-blooded about it, than would even a civil war, where some of the blame would necessarily fall on the belligerents, and not on us. I'm not sure what motivates our invasion -- or the continued occupation. To judge from the guy currently tipped as the successor to Bremer, it's not the milk of human kindness. But hard-hearted realism ain't it either...
Which brings us back to the question of why Dubya's crew might plant weapons now. Like I said, it doesn't strike me as the likeliest of stories, if only because of the timing. Then again, they may have been deep enough in their self-delusion to expect to actually find something real before now -- and associates of the current administration, including one now tipped as Bremer's successor, have not been overly squeamish in the past about spilling the blood of, as someone once said, "dark-skinned people". So, you never know....
Late edit: I managed to post this one without the last paragraph of the main body, which made the postscript look a bit weird; and subsequently added yet another. Ooops...