Jackson Diehl lists some differences between Obama and Romney on foreign policy:

In other words, Obama probably would use force only if Iran actually tried to build a bomb, while a Romney attack could be triggered if Iran were merely close to acquiring all the means for a weapon — which it is.

So both candidates’ Iran policies are horrible, but Diehl correctly identifies the main reason why Romney’s is worse. I assume Diehl prefers Romney’s even more unreasonable position, but that isn’t important here. What matters is that Romney clearly does have a much lower threshold for launching an attack on Iran, and he claims to be willing to start a war against Iran because of the possibility that Iran might one day be able to build a nuclear weapon at some point. There is no excuse for waging a “preventive” war against Iran, but this wouldn’t even be “preventive.” Instead of discouraging Iran from building nuclear weapons, such an attack would virtually guarantee that outcome. Romney’s position is that he would be even quicker to use force against Iran with an even flimsier justification than Obama. Not only is he giving Obama an easy target during the election, but he is demonstrating why he shouldn’t be trusted with that much power.

Diehl’s column is useful for identifying the few real differences between the candidates. He says it is a “shame” that neither campaign is talking about these issues, but this week he will find that the Democrats will be quite pleased to do so. Biden has already been previewing some of the attacks we’ll be likely to see this week and over the next two months. By the end of the column, we can see why Romney has avoided talking about these things as much as some of his hawkish supporters would like. There isn’t one issue on Diehl’s list that it benefits Romney to bring up. Favoring slower withdrawal from Afghanistan when most Americans want the war to be over now is a losing position. If Romney is the candidate of even “more missile defense,” and it’s reasonable to assume that he is, he is also the candidate who will wreck relations with Russia. Most voters won’t care about that by itself, but taken together with all of the others it creates a picture of a future administration that is overly aggressive and inept at the same time. Americans have experienced that kind of “leadership” quite recently, and most of them are not interested in more.