My colleague Matthew Yglesias quotes the latest (very good) Newsweek article detailing how the war in Iraq undercut the original "war on terror."

By the beginning of 2002 -- when Osama bin Laden was still on the run after his narrow escape at Tora Bora, when the United States still enjoyed vast, strong international support in its effort to evict the Taliban and stabilize Afghanistan, when no member of the Bush Administration had publicly discussed the prospect of invading Iraq -- preparations to invade Iraq were already underway. They gutted the effort in Afghanistan.

It is easy to prove now, and was easy to figure out at the time, that the more the United States concentrated on Saddam Hussein, the less it could concentrate on Osama bin Laden. This was one of many reasons to oppose the war before it began: not just the direct costs it would bring inside Iraq but what we could bloodlessly call its opportunity costs elsewhere.

The story of this tradeoff is an old one. It has been told many places, including in a cover story I did for the Atlantic three years ago. (Subscribers only; subscribe!) Even then, when Iraq was less obviously a disaster, people let me put them on the record saying things like this:

"Had we seen Afghanistan as anything other than a sideshow," says Larry Goodson, a scholar at the Army War College who spent much of 2002 in Afghanistan, "we could have stepped up both the economic and security presence much more quickly than we did. Had Iraq not been what we were ginning up for in 2002, when the security situation in Afghanistan was collapsing, we might have come much more quickly to the peacekeeping and 'nation-building' strategy we're beginning to employ now."...

"During the wars in Afghanistan and Iraq, [Thomas] White was Secretary of the Army. Like most other people I spoke with, he offered an example or two of Iraq-Afghanistan tradeoffs, mainly involving strain on Special Forces or limits on electronic intelligence from the National Security Agency [consistent with the details in the latest Newsweek story]. Another man told me that NSA satellites had to be "boreholed" in a different direction—that is, aimed directly at sites in Iraq, rather than at Afghanistan.

But no one said that changes like these had really been decisive. What did matter, according to White and nearly everyone else I spoke with, was the knowledge that the "center of gravity" of the anti-terrorism campaign was about to shift to Iraq. That dictated not just the vaunted "lightness" of the invasion but also the decision to designate allies for crucial tasks: the Northern Alliance for initial combat, and the Pakistanis for closing the border so that al-Qaeda leaders would not escape. In the end neither ally performed its duty the way the Americans had hoped. The Northern Alliance was far more motivated to seize Kabul than to hunt for bin Laden. The Pakistanis barely pretended to patrol the border....

The desire to limit U.S. commitment had at least as great an effect on what happened after the fall of the Taliban. James Dobbins, who was the Bush Administration's special envoy for Afghanistan and its first representative in liberated Kabul, told me that three decisions in the early months "really shaped" the outcome in Afghanistan.

"One was that U.S. forces were not going to do peacekeeping of any sort, under any circumstances. They would remain available to hunt down Osama bin Laden and find renegade Taliban, but they were not going to have any role in providing security for the country at large. The second was that we would oppose anybody else's playing this role outside Kabul. And this was at a time when there was a good deal of interest from other countries in doing so." A significant reason for refusing help, according to Dobbins, was that accepting it would inevitably have tied up more American resources in Afghanistan, especially for airlifting donated supplies to foreign-led peacekeeping stations in the hinterland. The third decision was that U.S. forces would not engage in any counter-narcotics activities....

"I can't prove this, but I believe they didn't want to put in a lot of regular infantry because they wanted to hold it in reserve," Richard Clarke explains. "And the issue is the infantry. A rational military planner who was told to stabilize Afghanistan after the Taliban was gone, and who was not told that we might soon be doing Iraq, would probably have put in three times the number of infantry, plus all the logistics support 'tail.' He would have put in more civil-affairs units, too. Based on everything I heard at the time, I believe I can make a good guess that the plan for Afghanistan was affected by a predisposition to go into Iraq. The result of that is that they didn't have enough people to go in and stabilize the country, nor enough people to make sure these guys didn't get out."

It is an old story, and it is the fundamental case against Iraq. Not that it was a good idea, poorly executed, that in the right circumstances might have made us safer. Rather, that it was exactly the wrong idea, from the start, because it distracted us from the enemy who had really harmed us, and whom we had a reasonable chance of containing and crushing, and toward an unnecessary fight guaranteed to multiply the number of enemies we faced worldwide. It should be possible to make the case that clearly.

Then again, it should have been possible to make the case in 2004.

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