Much of the outside pressure, which also includes the increasing bite of fresh UN Security Council sanctions – coupled with deeper measures from the US, Europe and, most recently, South Korea – has been driven by Iran's controversial nuclear program.
But another source of tension hits closer to home: Iran’s harassment of its beleaguered opposition leaders.
Last week in Tehran, groups of hard-line vigilantes for five days surrounded, vandalized, and laid siege to the house of Mehdi Karroubi, the cleric and former opposition presidential candidate. The action aimed explicitly to prevent Mr. Karroubi from joining pro-regime marchers as they marked Jerusalem Day on Friday, an annual event of solidarity with Palestinians that was hijacked a year ago by the opposition Green Movement to protest fraud in the June 2009 presidential election.
In scenes reminiscent of the political violence that has sometimes marred Iran since the 1979 Islamic revolution, and long before that, last week firebombs were thrown by the mob and one of Karroubi’s bodyguards was beaten unconscious, the latest acts that prompted widespread condemnation inside and outside Iran.
The assault prevented Karroubi from joining the rally, as basiji militiamen broke down the front door and guards fired warning shots, according to the pro-opposition Sahamnews website. Security cameras were torn down, graffiti sprayed, and plainclothes men riding motorcycles used by pro-regime vigilantes came by the dozen.