If there's a war between the United States and Iran, it may well start on the water. After all, it's happened before. Twenty years ago American ships were under fire in the Persian Gulf, and mines laid by the mullahs' men nearly sank a U.S. guided missile cruiser. In April 1988 the American and Iranian navies fought the biggest air-sea battle waged since World War II. By the time it was over, carrier-based U.S. attack planes had sunk the frigate Sahand and disabled the frigate Sabalan, the pride of the Iranian navy.

That's why the comment by Defense Secretary Robert Gates on Tuesday about the brief deployment of a second U.S. aircraft carrier to the gulf was so terse and so telling. "I don't see it as an escalation," Gates said. "I think it could be seen, though, as a reminder."

Gates would know. He was deputy director of the Central Intelligence Agency back in 1988. He has seen firsthand the treacherous complexities, the bluff and the bloodshed, of war with Iran, whether fought in the shadows or on the high seas. And anyone who was out in the gulf at the time, as I was, can see similarities between then and now. But looking back at the last undeclared war with Iran, who is reminded of what, precisely? The challenge is to draw the right lessons.

For those who've forgotten those naval operations with computer-generated names like Earnest Will, Nimble Archer and Praying Mantis (and I suspect most people in the United States don't remember them at all), the best history I've read is "Inside the Danger Zone: The U.S. Military in the Persian Gulf, 1987-1988," by Harold Lee Wise, which came out last year from the U.S. Naval Institute Press. It's not only thoroughly researched, it reads like a Tom Clancy thriller—or, rather, better. And Wise too is worried about what's happening now.

As he sees it, any war with Iran today is going to involve a major naval component. Forty percent of the world's oil supply passes through the gulf on vulnerable tankers, he points out, and that would come under direct threat.

Wise, in a paper he sent me this week, argues there are three basic lessons to be gleaned from the fight 20 years ago: