Let's start here:
U.S. warns Iran that oil disruption 'will not be tolerated'
This threat is akin to Erdogan's promise to escort aid ships to Gaza. The only difference is that unlike the Turkish military, the Iranian military doesn't have any relationship with Israel or the US to preserve, nor is it at odds with the civilian leadership on foreign policy and national defense.
The US & UK squeezed Japan into action with an embargo. They're teasing a dog hoping it'll bite so they can justify to their public putting it down.
This would be a good way to knock Ron Paul off the map, as well. Not that this issue is about him, but it would kill his hopes in the caucuses if the American people are hit with headlines of war with Iran, presented to frame Iran as the aggressor. It will appear to discredit him to political laymen and average voters.
I don't think Iran will do it, it would be for them what Saddam invading Kuwait was for him. If they can bear the sanctions and continue forward with the nuclear program, without engaging in hostilities, the US and/or Israel will attack with no more casus belli than NATO did in Libya.
The point of these sanctions is to do what the US & UK did to Japan. They want to force the Iranian Navy to strike first, and then the US & UK will begin a bombing campaign lasting weeks.
The IDF will seize any Hezbollah and Hamas action, claim it's an Iranian proxy reprisal true or false, to do the same to Gaza and Lebanon. Turkey and France will go to work on Syria. The Saudi government will crack the heads of domestic Shia, and those in North Yemen and Bahrain, just out of the expectation they're going to cause trouble whether they do or don't. Between the growing Salafi bombings and the assault on Shia all around it, Baghdad will lose its mind, begin mass arrests and killings of prominent and ordinary Sunni alike.
It's funny because now the US is becoming friend's with Iran and even having talks with Hezbollah through London, and Netanyahu is just throwing tantrums. It turns out Obama wasn't willing to start a war with Iran on Israel or the Saudi's behalf, and now they're courting Shi'ites.