On just about every level, it is hard to imagine two presidential candidates as different as Barack Obama and Mitt Romney. But once you strip away the rhetoric and bombast of Romney’s visit to Israel and his speeches and interviews, you end up with two almost identical positions.

Taking both men at their word, they share the same basic view, which is that Iran must not be allowed to acquire nuclear weapons and if the only way to prevent this is a military strike, the United States must carry it out.

Romney himself underlined the agreement on this issue between him and the president in an interview with Haaretz last week when he said that “President Obama has said that a nuclear Iran is unacceptable. I feel a nuclear Iran is unacceptable. The term ‘unacceptable’ continues to have a meaning: It suggests that all options will be employed to prevent that outcome.”

The presumptive Republican presidential candidate also reiterated his position that a strike is undesirable while there may be other options. “I think I made it clear in my address in Herzliya [in January 2007] that a military option is by far the least attractive option, but it should not be ruled out. The military option should be evaluated and available if no other course is successful.”

There may be some variations in tone between the two and Romney was careful in his interview with Haaretz to conform to the tradition of not criticizing the president while on foreign soil. But in a speech last week in Reno, the Republican attacked Obama for not being tough enough in the negotiations with Iran, while failing to present an alternative coherent vision or policy of how he himself would handle the issue.

However, when you examine the likely scenarios that could play out regarding Iran, there seems very little chance of either candidate, if elected, choosing different courses of action. Here are the scenarios:

Iran gets close to crossing the nuclear threshold – If there is incontrovertible evidence that Iran is about to cross the red line and attain real atomic capability (that is, reaching the point where a military strike could not prevent this eventuality), the United States would have the choice of following the North Korean precedent and having Iran make a laughingstock of successive administrations that swore it would never happen, or launching an attack. The strategic implications of a nuclear Iran are too great to ignore, and both Obama and Romney would give the order to attack.

Iran attacks shipping in the Gulf – Any Iranian attack on shipping going through the vital Strait of Hormuz, no matter which national flag the attacked ship is flying, is a threat to the global economy and a direct challenge to the U.S. forces stationed in the area. It is impossible to imagine an American president allowing such an event to pass by without a response, and the moment Americans are firing on Iranians, it won’t just be a maritime battle. Once again, Obama and Romney would have to react in similar fashion here.

Iran attacks an American ally in the Gulf – If Iran attacks under any pretext one of the Gulf States that is a U.S. ally, it will be tantamount to an attack on the American forces that guarantee their security. The U.S. response will have to be devastating or else the last remaining superpower will lose all credibility in the region and allow a belligerent Iran to get away with whatever it likes. Another no-brainer for either man as president.

Iran does nothing – If Iran does not provoke the U.S. in any of the above ways but continues to refuse to budge on uranium enrichment in the diplomatic engagement, it will all boil down to how close Iran seems to be getting to a bomb. As long as they don’t make a sudden dash for the threshold and it seems like the sanctions are biting seriously into Iran’s economy, neither Obama nor Romney will rush for the military option.

Israel attacks Iran – If Israel decides to go it alone and launches an attack on Iran, the administration will be in a very difficult position, since Israel will have been seen to have acted alone. In this case, there may be a different tone in the statements coming out of the White House but whoever is sitting in the Oval Office will have no choice but to rush to Israel’s assistance and help it defend itself from the inevitable Iranian retaliation. Israel is too much of an asset to the U.S, and it is both politically and diplomatically beholden to it. At the very least, we will see, as we did in 1991, an airlift of missile-defense batteries to help protect Israel’s cities.

Israel plans to attack – This is the real riddle: What will an American president do if he learns that Israel is about to launch an attack on Iran? The accepted wisdom here is that in this case, the president would exert diplomatic pressure in attempt to dissuade Israel from acting unilaterally. But the really big question is how hard he would try.

In Jerusalem this week, Romney adviser Dan Senor told reporters that “if Israel has to take action on its own in order to stop Iran from developing the capability, the governor would respect that decision.”

But 24 hours later he was forced to backtrack and say that “[Romney] believes we should employ any and all measures to dissuade the Iranian regime from its nuclear course, and it is his fervent hope that diplomatic and economic measures will do so. In the final analysis, of course, no option should be excluded.”

The bottom line remains the same; on Iran, the differences between Obama and Romney are mainly in nuance. In any case, presidents may come and go but the core elements of America’s diplomatic, national-security and intelligence establishments and most crucially, its own national interest, will remain essentially the same. Whoever wins in November, U.S. policy on Iran will not change.