Max Fisher writes: There are a number of very good reasons that the U.S. should want to keep Iran from getting a nuclear bomb: it would destabilize the already unstable Middle East, give Iran greater cover for adventurism abroad, provoke Israel and possibly Saudi Arabia, and increase the possibility of nuclear war. But one of those reasons is not, as Newt Gingrich put it at a recent event in central Florida, “If Iranians get nuclear weapons, they don’t have to fire a missile. They can just drive a boat into Jacksonville. Drive a boat into New York harbor.”

Iran is not going to park a nuclear-armed boat at the ports of Jacksonville, New York, or any other American city. There are a number of reasons why — I explain a few of them below — but what’s more important than the wrongness of Gingrich’s comment is the dangerous trend it represents.

Republican presidential candidates have been fighting to outdo one another on who can build Iran up as the scariest and most immediate threat. Mitt Romney named it the greatest threat since the Soviet Union, Herman Cain called for outright regime change, Michele Bachmann suggested they were dead set on sparking “worldwife nuclear war.” The politics of this are obvious and easy; the scarier you make Iran, the more likely voters are to prefer your confrontational rhetoric. People respond to fear, and it’s easier to understand “Iran is evil” than the complexities of why an isolated Iranian regime might seek nuclear capability and how they would use it. But this increasingly outlandish fear-mongering is dangerous in itself.

Imagine you’re a high-level Iranian official. All your adult life the only system you’ve known is Iran’s, which is nominally quasi-democratic but strictly authoritarian, a system where everybody gets in line behind the Supreme Leader, whose bidding is law. You hear reports that a prominent American official named Newt Gingrich, whom your advisers tell you could become the next American president, is playing up the threat you pose to the U.S. and openly contemplating a preemptive war against you. Do you respond by shrugging off his comments as meaningless campaign rhetoric that would probably not translate into policy, or do you start thinking about how to defend your country from this apparently erratic threat?

The Republican primary field’s exaggeration of the Iranian threat might make for good politics, but it misleads both Iranian leaders as well as U.S. voters, making both of them more likely to make bad choices. The U.S.-Iran relationship is complicated and dangerous enough without Gingrich or others disseminating bad information. People tend to behave irrationally and aggressively when they believe they are cornered. This is the situation that some Republicans are trying to portray, with violence as our only option. Iranian leaders may be increasingly perceiving that they are cornered as well (with plenty of help from whomever is killing those Iranian scientists), and according to a U.S. intelligence report, may see attacking the U.S. directly as an increasingly attractive defensive option. There’s a lot more than just campaign trail alarmism at play here, but with Gingrich and Romney doing seemingly whatever they can to hype the danger and terrify people, it certainly isn’t helping.

Fisher goes on to enumerate the reasons why Iran would not contemplate using a nuclear weapon against the United States. Neither, for similar reasons would it be likely to consider using nuclear weapons offensively against anyone else.