Here’s a prediction. There will be no war between the US and Iran this spring despite the Iranian threat to close the Straits of Hormuz. The Iranians are of course saying they might do this either to a) all shipping or b) just a US aircraft carrier making the return trip to Bahrain. But they won’t.
Closing the Straits, which (outside Iran’s coastal strip) are international waters, would be a clear justification for using force under international law. The list of people who would be using force in that eventuality would obviously start, although maybe not end, with the Americans. The US Navy and Air Force would, sooner or later, assemble sufficient forces to a) smash the Iranian navy and the naval bits of the Revolutionary Guards; b) any site associated with the Iranian nuclear effort; c) at least some of Iran’s oil infrastructure (rigs, refineries, pipelines etc).
The Iranian power structure could probably bear a)- no point having armed forces full of potential martyrs if you’re not prepared to risk them now and then. It might or might not be sanguine about b)- they seem to have gone to very great lengths to make it difficult to damage the key nuclear installations, and they may calculate that any bombing and cruise missile campaign might cause only temporary damage. But I really don’t think they will want to risk c)- damage to their oil infrastructure.
Iran is unable to export any worthwhile portion of its massive gas reserves because it would have to liquefy the gas to export a lot of it, and the only firms which make the (complicated and expensive) machinery needed to liquefy natural gas are all American, bar one. A German firm is trying to enter the market, so it really, really doesn’t want to show up on any State Department sanctions lists.
Right now, about the only way the Iranian government can earn foreign currency is to ship oil overseas. The current sanctions regime is not tight enough to completely prevent Iranian oil exports. The UK-France-Germany troika are pushing through tightened EU sanctions which should reduce the amount of oil the Iranians can sell to the Europeans, but even then they will still be able to sell some- more than the US (and the UK/France/Germany) would like.
That’s a big problem for Washington: sanctions on the Iranian oil industry aren’t as tight as it wants. But this problem would be greatly reduced if one could lob a few dozen cruise missiles at certain Iranian harbours and oil rigs. Which one could, if one’s Iranian opponent were foolish enough to give one a legally justifiable casus belli.
I don’t think that Obama would do anything crazy like blowing up all the Iranian oil storage tanks, but if the Iranians started a shooting war (which is what they would be doing by blocking the Straits) then I think the White House would be quite happy to order attacks on key oil installations. Bang go a few refineries, and up in smoke goes Iran’s ability to earn foreign currency.
Attacks on refineries would quite possibly be illegal as a response to an Iranian blockade of the Straits, but we’ve seen that Obama isn’t terribly worried about, say, sending helicopters full of armed troops across the airspace of a foreign country. I rather doubt he’ll lose too much sleep about getting tough if the Iranians pick a fight with him.
Bottom line: who has most to lose if a shooting war starts? I think it’s Iran- so the Iranian leaders won’t start such a war now, if they are rational. Are they rational? They are horrifically unpleasant people, certainly, and quite bonkers when it comes to ‘the truth about the Holocaust’, say, or the interpretation of Sharia law. But up to now they’ve shown themselves to be pretty cool players of power politics in a rough region, so I repeat that I don’t think they will block the Straits this spring.
One final question is why, in that case, the Iranians are even threatening to do so. I’m really not an Iran expert, so I’m inclined to believe the reason that I’ve seen advanced in the papers- there will be parliamentary elections in 2 March and the government needs to gin up a row with the Americans, and preferably also the Israelis, to have at least a little popular support.