One piece of conventional wisdom that's been taking shape for a while now is that there's not much difference between Mitt Romney and President Obama on foreign policy. As Peter Baker wrote Saturday in the New York Times, the differences seem largely "a matter of degree and tone." For example, "both would try to stop Iran's nuclear program through sanctions and negotiations without ruling out a military option."

Not so fast! Yesterday, the day after Baker's piece appeared, the Romney campaign highlighted a clear difference between the two candidates on Iran. So far as Obama is concerned, military force should be used only if required to keep Iran from getting a nuclear weapon. So far as Romney is concerned, Israel can start a war with Iran any time it wants, and America will join in the festivities.

To be fair: Romney didn't use the word "festivities." In fact, his new position was obscured by some technical terminology. And the labor of spelling his position out was divided between Romney and a foreign policy adviser. Still, the position becomes clear when you review yesterday's events:

First, shortly before Romney's big speech in Jerusalem, adviser Dan Senor made headlines with this utterance:

"If Israel has to take action on its own, in order to stop Iran from developing that capability, the governor would respect that decision," Mr. Senor said. Previewing Mr. Romney's remarks, Mr. Senor explained: "It is not enough just to stop Iran from developing a nuclear program. The capability, even if that capability is short of weaponization, is a pathway to weaponization, and the capability gives Iran the power it needs to wreak havoc in the region and around the world."

The key word here--used four times by Senor--is "capability". Nuclear weapons "capability" is a technical term, but, unlike many technical terms, it has no agreed-upon definition (as Ali Gharib noted yesterday). It refers to having the wherewithal to develop nuclear weapons should you decide to do so. Pretty much everyone would say that if Iran had the ability to develop nuclear weapons within three or four months, that would constitute "capability." Some would say that if Iran could develop them within nine months that would constitute "capability". And some would define the term even more broadly.