Iran is the coronated boogeyman, those scary Farsi speakers half a world away with much more to lose, and for the global power structure there is much more to gain. The blockade actions are described below accurately. I would first like to submit what a blockade is considered in legal terms(and how defined in U.S. legal theory), then to discuss the stated reasons for the blockade. Finally I will drop a few links ripped from the headlines, all providing a grim and real illustration for the potential of war with Iran.
A blockade, noted by Wikipedia(as defined by the Encyclopedia Britannica) is: "an act of war by which a belligerent prevents access to or departure from a defined part of the enemy’s coasts". In a thorough article on blockades as an act of war, author Stephen Lendman states U.S. definitions of blockades, as well as declarations that the U.S. has accepted and are binding, all pointing to blockades as being an act of war.
Similarly, there is a concept called Casus Belli which is Latin for 'justification for acts of war'.
I think some will appreciate this analogy, although one is free to make their own decision on its application. To try to find a similar action involving blockades, take Israel's experience with the Six Day War, where the "Israeli government had a short list of casī bellorum, acts that it would consider provocations justifying armed retaliation. The most important was a blockade of the Straits of Tiran leading into Eilat, Israel's only port to the Red Sea, through which Israel received much of its oil. After several border incidents between Israel and Egypt's allies Syria and Jordan, Egypt expelled UNEF peacekeepers from the Sinai Peninsula, established a military presence at Sharm el-Sheikh, and announced a blockade of the straits, prompting Israel to cite its casus belli in opening hostilities against Egypt."
Although there is a tacit and unspoken assumption in the U.S. and Israel that we never apply the same standards to our enemies, this is an interesting situation. If we use an accepted definition in the United States for blockades being an act of war, as well as assuming Israel was justified in its conduct of starting a conflict while using blockades as a justification, then by applying the same logic, would Iran not be correct in at least stating that this is an act of war, one by which(using Israels logic) they would be justified in retaliating? Whether or not this is correct is sort of useless, as Iran would be insane to retaliate, playing exactly into its enemies hand.
At the same time, it is insane to punish a sovereign nation for moving to build nuclear power plants, an action which the IAEA is actually required to support and assist with. This leads into the stated justifications for the blockade.
The United States and others are blockading/sanctioning Iran because they claim that there are unanswered questions about Iran pursuing Nuclear Weapons, and the Iranians are not forthcoming enough with clearing up these ambiguities. Now, I leave open the possibility that Iran might have conducted some research into the issue, although it is widely agreed on all sides that this halted in 2003. Also, much of the questions arose from the 'Smoking Laptop' provided by the M.E.K. to I believe was Israel. The M.E.K. is a U.S. designated terrorist organization. Reporting on the smoking laptop can be found here and here.
Although I don't support further access to destructive weaponry, I do not support this blatant aggression based on questionable information. Also, the IAEA has been able to continue to verify the non-diversion of nuclear material in Iran. That organization has the closest eyes on Iran's nuclear program, and should be supported in efforts to continue to keep Iran transparent. So whether or not Iran did research or testing on weapons delivery capabilities, they have not diverted any material for that purpose.
Finally, just to provide a quick context around the idea that Iran is the next target, check out the top three links right now at Antiwar.com, you can decide yourself how credible, but informative it is.
Pentagon Requests Mightier Bomb to Attack Iran
The 30,000-pound bunker-busters are designed to penetrate Iran's underground nuclear facilities
by John Glaser, January 28, 2012
Iran Finalizes Bill for Immediate Ban on Oil Exports to Europe
Iran is preempting an EU embargo on their oil, an illustration of how ineffective sanctions are
by John Glaser, January 28, 2012
Israel warns time is running out before it launches strike on Iran
Growing body of opinion suggests that Iranian response to an attack would be muted.
The flimsy justifications for war with Iraq taught me a very useful lesson. Iran is a bigger country, and the justifications may follow the same pattern. I am not willing to support an insane incursion on behalf of the United States or Israel on the current grounds, it will take a Titanic-sized amount of propaganda to sink my stance. Peace and Love.