What's going on in Iran, again?

Another curious explosion in Iran, this time in Isfahan, the center of Iranian nuclear weapons research.  We've seen this before, of course.  The Washington Post gives a rundown of the known incidents:

A massive blast at a missile base operated by Iran’s Revolutionary Guard Corps nearly two weeks ago was the latest in a series of mysterious incidents involving explosions at natural gas transport facilities, oil refineries and military bases — blasts that have caused dozens of deaths and damage to key infrastructure in the past two years.
Iranian officials said the Nov. 12 blast at the missile base was an “accident,” and they ruled out any sabotage organized by the United States and its regional allies. The explosion on the Shahid Modarres base near the city of Malard was so powerful that it shook the capital, Tehran, about 30 miles to the east.

Despite the official denial of foreign involvement in the latest blast, suspicions have been raised in Iran by what industry experts say is a fivefold increase in explosions at refineries and gas pipelines since 2010.
Explaining the increased number of industrial incidents is proving to be a predicament for Iranian leaders, who do not want to appear vulnerable at a time when Israeli leaders have been debating military intervention against Iran over its controversial nuclear program.


[...]

At least 17 gas pipeline explosions have been reported since last year, compared with three in 2008 and 2009. At the same time, nearly a dozen major explosions have damaged refineries since 2010, but experts say it is complicated to determine the cause of such incidents.

Could the US be behind them? Yeah, I wish:

In the United States, Republican presidential contenders have called for President Obama to start covert action against Iran because of its refusal to stop its uranium-enrichment program. U.S. officials suspect the program is aimed at producing fissile material for nuclear weapons. Iran insists that it wants only to make its own fuel for nuclear power plants.
Suspicions that covert action might already be underway were raised when four key gas pipelines exploded simultaneously in different locations in Qom Province in April. Lawmaker Parviz Sorouri told the semiofficial Mehr News Agency that the blasts were the work of “terrorists” and were “organized by the enemies of the Islamic Republic.”
[...]

“We are not ruling out sabotage in the Malard missile base,” said one source close to the Revolutionary Guards, speaking on condition of anonymity because of the sensitivity of the subject. “It is not impossible to bribe a single person into doing something bad.”
On Wednesday, an explosion rocked a stronghold in southern Lebanon of Iran’s regional ally, Hezbollah, which is widely believed to be supplied with Iranian missiles capable of hitting major urban centers in Israel. Hezbollah did not comment on the cause of the blast but denied that it occurred at one of the group’s arms depots, Beirut’s Daily Star newspaper reported.
Iran has accused the United States and Israel of organizing the assassinations of three nuclear scientists in Tehran since 2010. The government has also blamed both countries for a computer virus called “Stuxnet,” which President Mahmoud Ahmadinejad acknowledged had disabled centrifuges used to enrich uranium.

What does it mean?  Michael Ledeen has been on top of it:

Another week, another explosion at or near an Iranian military installation (or is it a nuclear research facility?).  As usual, the regime doesn’t know what to say.  The mullahcracy is so intensely divided that different “spokesmen” from different ministries/news outlets/cults/mafias put out different versions.  There was an explosion, or at least “the sound of an explosion.”  This goes out on the wires.  Then, no, there was no explosion, it was just the sound of our fierce military training.  Then again, yes, there was something, but not to worry, just go home and shut up.  And so it goes in the Islamic Republic of Iran, as our president so loves to call his intended international partners.

A big reason why I highly doubt the US is behind this.  More likely an internal uprising that Ledeen has been predicting:

Since I’m pretty much the only guy in town who forecast the war against the mullahs, and it’s now so obvious that even MSM reporters and columnists can mention it without blushing, I’m sticking to my story.  I don’t think the ongoing assault against the regime is coming from outside Iran.  I think it comes from the Iranian opposition within the country.  And I think it shows that the opposition is a great deal stronger than the experts have opined.
If you were Supreme Leader Ali Khamenei, what would you be saying to that unhealthy face in the mirror?  You’d say, “they come and go at will;  they obviously have the full cooperation of traitors at very high levels of the regime, even inside the Guards.  They not only knew Moghaddam was going to be there, but exactly where and when.  Now Isfahan, another heavily guarded base.  That doesn’t look like Zionists and infidels, whose pathetic collaborators we round up easily over and over again;  it looks like people who are trusted and supported by the traitors in my own house.”
When a regime cracks, even very high officials start to do favors for the opposition, hoping to avoid the worst if the regime comes down.  Khamenei knows that the head of the shah’s secret intelligence service went on to hold the same position under the fanatical Ayatollah Khomeini.  Recent events will have convinced the supreme leader that his own security may be as compromised as the shah’s was.
Add to this the dreams common to regular users of opium (Khamenei is one of them) and you’ve got a very explosive situation.

No pun intended, I'm sure.