That's because al-Qa'ida is changing from a simple group into a global philosophy.
Small groups of individuals in areas with no history or links to terrorism can become radicalized with AQ inspired propaganda. They can go to jihadist websites and put together their own plots with their own resources. The term 'home grown terrorists' is a dismissive and naiive way of portraying what will be an increasingly commong threat. It's the jihadist equivalent of yelling "I am Sparticus"
Insofar as we defeat al-Qa'ida proper, that doesn't end the threat anymore. It's too late for that. The next generation al-Qa'idas are already in the incubator.
For example many in the US are still thinking in terms of "body counts" (the "Terrorst Magnet" theory).
In a war of this type, body counts are almost entirely irrelevant. The center of gravity in this kind of warfare isn't in units, manpower, or equipment. It's the social makeup of the Muslim communities themselves. As a U.S. doctor serving in the Korean war commented, on the Chinese, "The womb may yet prove to be the most effective weapon of all". So long as those communities are inclined to support extremism, or, more commonly, to not actively combat it, enemy reinforcements will never be far behind.
In this light, our position in Iraq appears particularly unfortunate.
It's unfortunate only in that we tried to use the military as a crutch, in light of a poor post-war political reconstruction effort. We are effectively invincible from a military standpoint, but unable to attain victory. That enduring stalemate provides ample propaganda to recruit new jihadists the world over.
And when we do the, Jihadists will take credit for our "expulsion", and many will believe them, further increasing their influence. (This is exactly what happened in Afghanistan - Al Qaeda played a very minor role in that conflict, but Al Qaeda successfully trafficked in inflated accounts of its importance in expelling the Russians for a decade thereafter.)
At this point, even if it ends in a draw, with both sides able to claim some sort of partial success, it will be a Phyrric victory. Al-Qa'ida may be broken in Afghanistan and Iraq, but a new generation of terrorists have cut their teeth on the U.S. military. The new jihadists will take home lessons that will be taught again, posted on the internet, and preached in mosques.
The idea of Arab resistance to foriegn aggression is a romantic one that sells very well in the Middle East. There doesn't have to be much tangible gain for the myths to be spread, and for Arabs to feel pride and motivation over it.
Meanwhile, we have 100,000 plus high-tech troops, at a cost of 30-50 billion dollars a year, fighting a shadowy enemy who is successfully attacking them with roadside bombs made for $10 or less from a salvaged artillery round.
Coming soon to a roadside near you. Iraq, if nothing else, has taught jihadists how easy and inexpensive it can be to fight us, even at our strongest.
Under these conditions from the Jihadist prespective – and more important to many in the Islamic world - our victories are the result of the criminal application of massive fire power – the frustrated lashings out of a wounded giant – while any Jihadist success against our troops is a valiant act of resistance successfully undertaken again enormous odd.
It's a romantic myth of battle and courage, but it's what they want to believe. Those tales inspire religious Muslims into radicalism, by playing upon their pride, sense of community, and religious faith. The mosques will radiate these myths into their members, and networks will form.
But as the situation has actually developed, whatever Al Qaeda’s role in Iraq at the end of our involvement in that sorry country, in the battle with “Islamic Terrorism” writ large we are almost certainly going to “lose” in Iraq.
Victory is not yet out of our grasp, but, unless we really get our act together and turn Iraq around, the jihadists will also walk away with considerable winnings. Those spoils many not be much more than experience, credibility, and terrorist contacts, but it'll be enough to nurture a global jihad still in it's infancy.
I don't think that current leadership of either party can admit this, or formulate realistic plans to extract us from this mess - their reputations are on the line, and it's just to tempting to "kick the can down the road" and hope the next guy will take the blame.
We're going to be in this war for decades.
But in the meantime, we can continue to educate ourselves about the history, aims, and strengths and weaknesses of the Radical Islamic movements that have turned to terrorism and how they relate to the broader course of Islamic thought (and I'll say it again "The Looming Tower" is a good place to start).
The best chance we have of winning is in understanding the problem, and I completely agree with you there. Informed debate and clear thinking is the only way out of this maze. That said, prepare to be flamed, and flamed hard, for seeking answers outside of the party line.
I don't know... is there still a "party line"?
There is an administration position, "stay the course", and there are various positions on the alternatives, but the sense I get is that increasingly people have a desire for some realistic, straight talk about viable alternatives to just sitting there, taking casualties, and waiting for the various factions in Iraq to somehow resolve their political problems. And it seems to me that more and more people would settle for de facto partition (“Those are just the facts on the ground”), or total chaos or a functioning coalition government composed of members willing to agreed to disagree long enough to ask us to leave (“You can’t save people from themselves”) or a more pressing crisis that required out troops elsewhere (if we discovered that North Korea was selling nuclear weapons to terrorists, would anyone care much what happened once they left Iraq if our troops there were needed in NK to deal with an imminent threat to the mainland US?) – that is for just about any resolution that gave us a face-saving way out, petty much irrespective of what we left behind.
Meanwhile, though we don’t know what’s next, it’s not clear to me that a “party line” is left to follow which can unite people either here or elsewhere as we search for a “next step”.
And it’s in this light that IMO you have to look (for example) at the various geopolitical arguments often made by those who consider themselves pragmatic supporters of a continued occupation - the “unsinkable aircraft carrier” and “access to oil” arguments and so on – unless we find leadership better able to unite the country behind the means to such ends, they are fantasy.