Adm. Fallon’s (forced?) resignation was the last warning we are likely to get of an attack on Iran. It does not mean an attack is certain, but the U.S. could not attack Iran so long as he was the Centcom commander. That obstacle is now gone.

Vice President Cheney’s Middle East tour is another indicator. According to a report in The American Conservative, on his previous trip Cheney told our allies, including the Saudis, that Bush would attack Iran before the end of his term. If that report was correct, then his current tour might have the purpose of telling them when it is coming.

Why not just do that through the State Department? State may not be in the loop, nor all of DOD for that matter. The State Department, OSD, the intelligence agencies, the Army, and the Marine Corps are all opposed to war with Iran. Of the armed services, only the Air Force reportedly is in favor, seeking an opportunity to show what air power can do. As always, it neglects to inform the decision-makers what it cannot do.

The purpose of this column is not to warn of an imminent assault on Iran, though personally I think it is coming, and soon. Rather, it is to warn of a possible consequence of such an attack. Let me state it here, again, as plainly as I can: an American attack on Iran could cost us the whole army we now have in Iraq.

Lots of people in Washington are pondering possible consequences of an air and missile assault on Iran, but few if any have thought about this one. The American military’s endless “we’re the greatest” propaganda has convinced most people that the U.S. armed forces cannot be beaten in the field. They are the last in a long line of armies that could not be beaten, until they were.

Here’s roughly how it might play out. In response to American air and missile strikes on military targets inside Iran, Iran moves to cut the supply lines coming up from the south through the Persian Gulf (can anyone in the Pentagon guess why it’s called that?) and Kuwait on which most U.S. Army units in Iraq depend (the Marines get most of their stuff through Jordan). It does so by hitting shipping in the Gulf, mining key choke points, and destroying the port facilities we depend on, mostly through sabotage. It also hits oil production and export facilities in the Gulf region, as a decoy: we focus most of our response on protecting the oil, not guarding our Army’s supply lines.

Simultaneously, Iran activates the Shi’ite militias to cut the roads that lead from Kuwait to Baghdad. Both the Mahdi Army and the Badr Brigades  the latter now supposedly our allies  enter the war against us with their full strength. Ayatollah Sistani, an Iranian, calls on all Iraqi Shi’ites to fight the Americans wherever they find them. Instead of fighting the 20 percent of Iraq’s population that is Sunni, we find ourselves battling the 60 percent that is Shi’ite. Worse, the Shi’ites’ logistics lie directly across those logistics lines coming up from Kuwait.

U.S. Army forces in Iraq begin to run out of supplies, especially POL (petroleum, oil, lubricants), of which they consume a vast amount. Once they are largely immobilized by lack of fuel, and the region gets some bad weather that keeps our aircraft grounded or at least blind, Iran sends two to four regular army armor and mech divisions across the border. Their objective is to pocket American forces in and around Baghdad.

The U.S. military in Iraq is all spread out in penny packets fighting insurgents. We have no field army there anymore. We cannot reconcentrate because we’re out of gas and Shi’ite guerrillas control the roads. What units don’t get overrun by Iranian armor or Shi’ite militia end up in the Baghdad Kessel. Gen. Petraeus calls President Bush and repeats the famous words of Ducrot at Sedan: Nous sommes dans un pot de chambre, et nous y serons emmerdés. Bush thinks he’s overheard Petraeus ordering dinner  as, for Bush, he has.

U.S. Marines in Iraq, who are mostly in Anbar province, are the only force we have left. Their lines of supply and retreat through Jordan are intact. The local Sunnis want to join them in fighting the hated Persians. What do they do at that point? Good question.

How probable is all this? I can’t answer that. Unfortunately, the people in Washington who should be able to answer it are not asking it. They need to start doing so, now.

It is imperative that we have an up-to-date plan for dealing with this contingency. That plan must not depend on air power to rescue our Army. Air power always promises more than it can deliver.

As I have warned before, every American ground unit in Iraq needs its own plan to get itself out of the country using only its own resources and whatever it can scrounge locally. Retreat to the north, through Kurdistan into Turkey, will be the only alternative open to most U.S. Army units, other than ending up in an Iranian POW camp.

Even if the probability of the above scenario is low, we still need to take it with the utmost seriousness because the consequences would be so vast. If the United States lost the army it has in Iraq, we would never recover from the defeat. It would be another Adrianople, another Manzikert, another Rocroi. Given the many other ways we now resemble Imperial Spain, the last analogy may be the most telling.

I have said all this before, in previous columns and elsewhere. If I sound like Cassandra on this point, remember that events ended up proving her right.