Why the Pentagon Thinks Attacking Iran is a Bad Idea

Iranian soldiers on parade for President Ahmadinejad.

The widely held view within the Pentagon is that any military strike on Iran would be a dangerous, highly complicated undertaking. "There's a lot about Iran that we still just don't understand," says the senior military official. "They are very, very hard to predict." Adds the defense analyst, "A lot of generals are saying, 'Are you sure you really want to do this? Are the gains worth the risk?' "

Shadow games. In scenarios routinely war-gamed by the Pentagon, the recurring answer tends to be no. The risks are considerable, and these shadow games—conceptual exercises intended to test out ideas—often end badly for the U.S. side. "In so many scenarios, it's a nightmare," says Bruce Riedel, a former CIA officer and Middle East fellow with the Brookings Institution who has taken part in war games.

One of the biggest nightmares, a land invasion of Iran, is widely dismissed as a nonstarter. "Unless it's happened in the deepest recesses of the Pentagon, I've never been involved in a war game that seriously considered a land invasion of Iran," says the defense analyst. At the Command and General Staff College in Fort Leavenworth, Kan., Maj. Bruce Terry estimated in his widely circulated master's thesis last year that it would take at least four years to mobilize the more than 1 million U.S. troops required for such an endeavor, followed by U.S. casualties in the tens of thousands for each year of occupation.

The working war scenarios involve surgical strikes by cruise missiles and warplanes on key targets, such as Revolutionary Guard facilities and Iranian nuclear sites, often coupled with covert operations on the ground. These attacks have been war-gamed regularly since 2004, according to another defense adviser, and the results point to some considerable stumbling blocks. "The No. 1 problem we have is: 'Where are the targets?' We still have trouble accurately locating all of the pieces of the nuclear program that we need to take out in order to have a relatively decisive effect," says Bacevich.

That uncertainty extends to assessments of when Iran could have nuclear-bomb capability, something that Iranians assert is not their plan. The consensus U.S. intelligence view points to the 2010 to 2015 timeframe, while Israeli estimates predict it as soon as late 2009. The differences reflect disagreements about the intelligence, as well as about what level of capability should be viewed as the weapons threshold.

What is clear is that Iranian nuclear facilities are buried, dispersed, and protected—and U.S. bombs may not be able to reach deeply enough to destroy them. Some are also in close vicinity to schools, hospitals, and other facilities where there could be civilian casualties that would further inflame anti-Americanism across the Muslim world. By most accounts, bombing might set back Iran by only a few years—at a high cost to the United States.

Such strikes come with the prospect of retaliation in the Strait of Hormuz, though such a move would cut off Iran's own oil exports as well. It is a narrow chokepoint, and an Iranian attempt to obstruct tanker traffic would cause oil to soar far above even recent record prices with dire consequences for western economies. Iran could employ swift boat-swarming tactics and the threat of Chinese-made antiship cruise missiles launched from patrol boats and from small islands off its coast. "The Strait is always the key for war games in the Gulf," says Paul Van Riper, a retired Marine three-star general who unleashed an imaginary salvo of Silkworm-style missiles, overwhelming the sensors on U.S. warships, while playing a "red team" country that closely resembled Iran in a now legendary 2002 war game.

"High stress." There is, too, the issue of mines. "Nobody's underestimating Iran's ability to disrupt access to the strait," adds a senior Navy officer who recalls serving on a U.S. warship accompanying Kuwaiti oil tankers in 1988. "People brush over the tanker wars, but the Navy hasn't forgotten," he says. "It was high stress," and two Navy ships were heavily damaged by mines. Despite antimine technology, the officer recalls that the crew set up a chair and built a shade for it, so that a seaman on deck could scan the water round-the-clock for mines. The Navy practiced repelling swarming Iranian swift boats and mounted machine guns for just such an event on the side of its ships.