Krugman:

Attacking Iran would be a catastrophic mistake, even if all the allegations now being made about Iranian actions in Iraq are true.

But it wouldn’t be the first catastrophic mistake this administration has made, and there are indications that, at the very least, a powerful faction in the administration is spoiling for a fight.

Before we get to the apparent war-mongering, let’s talk about the basics. Are there people in Iran providing aid to factions in Iraq, factions that sometimes kill Americans as well as other Iraqis? Yes, probably. But you can say the same about Saudi Arabia, which is believed to be a major source of financial support for Sunni insurgents — and Sunnis, not Iranian-backed Shiites, are still responsible for most American combat deaths.

The Bush administration, however, with its close personal and financial ties to the Saudis, has always downplayed Saudi connections to America’s enemies. Iran, on the other hand, which had no connection to 9/11, and was actually quite helpful to the United States in the months after the terrorist attack, somehow found itself linked with its bitter enemy Saddam Hussein as part of the “axis of evil.”

So the administration has always had it in for the Iranian regime. Now, let’s do an O. J. Simpson: if you were determined to start a war with Iran, how would you do it?

First, you’d set up a special intelligence unit to cook up rationales for war. A good model would be the Pentagon’s now-infamous Office of Special Plans, led by Abram Shulsky, that helped sell the Iraq war with false claims about links to Al Qaeda.

Sure enough, last year Donald Rumsfeld set up a new “Iranian directorate” inside the Pentagon’s policy shop. And last September Warren Strobel and John Walcott of McClatchy Newspapers — who were among the few journalists to warn that the administration was hyping evidence on Iraqi W.M.D. — reported that “current and former officials said the Pentagon’s Iranian directorate has been headed by Abram Shulsky.”

Next, you’d go for a repeat of the highly successful strategy by which scare stories about the Iraqi threat were disseminated to the public.

This time, however, the assertions wouldn’t be about W.M.D.; they’d be that Iranian actions are endangering U.S. forces in Iraq. Why? Because there’s no way Congress will approve another war resolution. But if you can claim that Iran is doing evil in Iraq, you can assert that you don’t need authorization to attack — that Congress has already empowered the administration to do whatever is necessary to stabilize Iraq. And by the time the lawyers are finished arguing — well, the war would be in full swing.

Finally, you’d build up forces in the area, both to prepare for the strike and, if necessary, to provoke a casus belli. There’s precedent for the idea of provocation: in a January 2003 meeting with Prime Minster Tony Blair, The New York Times reported last year, President Bush “talked about several ways to provoke a confrontation, including a proposal to paint a United States surveillance plane in the colors of the United Nations in hopes of drawing fire.”

In the end, Mr. Bush decided that he didn’t need a confrontation to start that particular war. But war with Iran is a harder sell, so sending several aircraft carrier groups into the narrow waters of the Persian Gulf, where a Gulf of Tonkin-type incident could all too easily happen, might be just the thing.

O.K., I hope I’m worrying too much. Those carrier groups could be going to the Persian Gulf just as a warning.

But you have to wonder about the other stuff. Why would the Pentagon put someone who got everything wrong on Iraq in charge of intelligence on Iran? Why wasn’t any official willing to take personal responsibility for the reliability of alleged evidence of Iranian mischief, as opposed to being an anonymous source? If the evidence is solid enough to bear close scrutiny, why were all cameras and recording devices, including cellphones, banned from yesterday’s Baghdad briefing?

It’s still hard to believe that they’re really planning to attack Iran, when it’s so obvious that another war would be a recipe for even bigger disaster. But remember who’s calling the shots: Dick Cheney thinks we’ve had “enormous successes” in Iraq.