Andrew Sullivan does a good job of answering a couple of Michael Kinsley's "tough" questions.

How has an attack on the United States by a terrorist group based in Afghanistan led us to war against Iraq?

9/11 revealed how vulnerable the United States is to international Islamist terrorism. It revealed the absolute ruthlessness of the enemy. It also revealed the possibility of a nightmare chemical, biological or nuclear 9/11. For twelve years, the United States and others have been trying to get Saddam Hussein to get rid of his weapons of mass destruction. 9/11 made resolving that issue far more urgent, since there was a clear possibility that Saddam could deliver such weapons to some of his terrorist clients. So we decided to get serious about Saddam. How hard is that argument to grasp? The linkage was there from the very beginning. Yours truly even mentioned Iraq as a state sponsor of such terror the very week of September 11.

Why are nuclear weapons in Iraq worth a war but not nuclear weapons in North Korea?

Because Saddam doesn't have them yet but Kim Jong Il does. When the enemy has the capacity to create nuclear Armageddon, it obviously raises the risks of military intervention. Again: I'd have thought for a person of Kinsley's intellect, that rather elementary point would be a no-brainer.

And that second question is particularly dumb. Sullivan answers it well, but fails to point out the obvious contradiction in the question itself. When people ask "Why aren't we going to war with North Korea?" do they want to go to war with North Korea?

This, then, is an inherently pro-war question. Pro-war against North Korea. Because it damn sure isn't an argument for not going to war with Iraq.

Update: Eugene Volokh answers Kinsley's second question too.