Today is widely considered the crucial day of the Iranian crisis, which erupted when the ruling mullahs of the Guardian Council made their vote-rigging too obvious for their subjects to ignore.  Supreme Leader Ali Khamenei warned Iranians yesterday that his patience was at an end with protests, but activists claimed that they would defy Khamenei and gather again in cities to protest the government and the election results.  Today, sketchy reports have hundreds of police blocking access to key areas, including the use of teargas, to keep protestors out:

Heavily armed police prevented several thousand Iranian protesters Saturday from entering Revolution Square — one of the main protest sites in Tehran, a witness told CNN.

About a mile away, police kept the crowd back by throwing two canisters of tear gas at their feet, the witness said.

The Web site of the main opposition candidate, Mir Hossein Moussavi, quoted news reports as saying a flood of people were headed to the capital from surrounding towns.

Thus far, we’ve seen attempts by the government to spread misinformation about the rallies, and confusion and hesitation among the organizers.  Protests today will almost certainly be an irrevocable act.  If the government doesn’t act with force to suppress the protests, the mullahs will lose all credibility and will have to run for their lives.  If they give the order to attack and the police don’t carry it out, they will have to run for their lives.  They know the stakes and the risk, but the alternatives for them are all bad; their backs are against the wall — but they still have all the guns, at least for now.

We’ll keep an eye on reports and update as the day goes along.  So far, it looks as though the confrontation will come.

Update (AP): Multiple Iranian twitterers are claiming there’s been some sort of explosion at Khomeini’s shrine, which they’re treating as the regime’s version of the Reichstag fire. There’s precedent for that in Iranian history, too.

Update (Ed): NBC’s Today has a good, if basic, report this morning:

Update (AP): The Khaleej Times says the explosion at Khomeini’s shrine was caused by a suicide bomber. Hmmm.

Update (AP): Two mind-blowing videos for you. The second is familiar; it’s clearly taken at the same assault on the Basij complex that I wrote about earlier this week. Watch all the way through and you’ll see Iranian protesters actually fall after being shot. I don’t know where the first clip is from — it was uploaded by BBC Persia today but could also be from the Basij complex incident a few days ago — but it’s the closest thing I’ve seen yet to all-out war.

As I write this, Iranian twitterers are reporting use of water cannons, teargas, gunshots, and even some sort of burning agent being dropped on the crowds by helicopters. There’s still no confirmation as far as I know that a bomb really did go off at Khomeini’s shrine, but Reuters is now reporting that Mousavi supporters have set fire to a building being used by Ahmadinejad supporters. And now, suddenly, Mousavi is making some sort of statement where he says he’s prepared for martyrdom. Sounds like the gloves are finally all the way off.

Update (AP): Anecdotally, after following them all week, I can tell you that the tone of Iranian twitterers is strikingly different from what it’s been before. Some are openly asking people to pray for them. The fear is palpable.

Here’s a poignant video in Farsi with English subtitles that’s making the rounds today. The din you hear in the background is Tehranians screaming “Allahu Akbar” in defiance of Khamenei last night.

Update (AP): A comparatively calm but significant new clip: According to NIAC, protesters can be heard chanting “Marg bar Khamenei,” i.e. “Death to Khamanei.” It’s not about Ahmadinejad anymore.

Update (AP): If you’re unfamiliar with the cast of characters in Iran, Time’s primer is useful. Meanwhile, new video of what the streets look like in Tehran today. Note the end, where a few protesters display nightsticks they’ve seized from the Basij — to cheers from the crowd.

Update (AP): To see just how bad things have gotten, brace yourself and click here. Strong content warning.

Update (AP): Mousavi knows the regime can’t let him walk free forever and is calling for a strike if he’s detained. Who steps in if he’s jailed, I wonder. Karroubi? Rafsanjani, whom Khamenei would be loath to arrest lest it inflame the clerics?

Gosh, if only the U.S. had troops stationed in some neighboring country or countries so that we could start feeding weapons to the protesters.

Update (AP): Not sure if this is wise under the circumstances, but Israel’s minister for strategic affairs is now openly predicting a revolution — with no resulting change in Iran’s nuke program. Meanwhile, a provocative report from NIAC:

This morning a friend of NIAC who gets Iranian Satellite TV here said that state-run media showed President Obama speaking about Iran this morning. However, instead of translating what he actually said, the translator reportedly quoted Obama as saying he “supports the protesters against the government and they should keep protesting.

Assuming this report is correct, it shows the Iranian government is eager to portray Obama as a partisan supporting the demonstrators.

Update (AP): A HuffPo reader reports that the news about a bombing at Khomeini’s shrine appears to be yet another regime lie:

“I’m watching state TV here in Dubai and they just did a report on the bombing at the mausoleum. There was NO DAMAGE. All they showed was a broken window saying the “terrorists” luckily blew themselves up outside the building before doing any damage inside. The “bombing” was clearly a fraud as there was NO DAMAGE done to the mausoleum other than a broken window they showed at the entrance of the building. It clearly looked like there was NO BOMBING, no explosion fragments or blood shown just one shattered window. Also a correction to my previous e-mail. The program said the youths had been talking to “friends” in the U.K. and the U.S. on the phone about causing destruction in Iran rather than actually going to the U.S. and being trained. Important difference but the subtext is the same. They’re clearly building a case for foreign interference i.e. the U.K and U.S.”

Update (AP): Dear god. Here’s another extremely graphic video of the murder of the young woman I linked up above. NIAC translates the Facebook description as follows: “A young woman who was standing aside with her father watching the protests was shot by a basij member hiding on the rooftop of a civilian house. He had clear shot at the girl and could not miss her. However, he aimed straight her heart. I am a doctor, so I rushed to try to save her. But the impact of the gunshot was so fierce that the bullet had blasted inside the victim’s chest, and she died in less than 2 minutes.”

Update (AP): Another one that’s going viral shot at Shiraz University. Note at about 90 seconds in how the police trap women against the gate and break out the nightsticks. Click the image to watch.

Update (AP): Multiple reports on Twitter now that people are shouting from the rooftops — literally — at Khamenei and the regime.

Update (AP): Verrry interesting: Rooftop shouts now being heard in Mashad, the Shiites’ second holiest city. Proof that the clerics are coming around to the people’s side?

Update (AP): Another murder in Tehran. Skip ahead to 3:25 to see the latest victim of Iran’s “robust debate,” or watch from the beginning and you’ll find protesters picking up rocks and chanting “Marg bar dictator.”

Update (AP): A statement from the White House:

The Iranian government must understand that the world is watching. We mourn each and every innocent life that is lost. We call on the Iranian government to stop all violent and unjust actions against its own people. The universal rights to assembly and free speech must be respected, and the United States stands with all who seek to exercise those rights.

As I said in Cairo, suppressing ideas never succeeds in making them go away. The Iranian people will ultimately judge the actions of their own government. If the Iranian government seeks the respect of the international community, it must respect the dignity of its own people and govern through consent, not coercion.

Martin Luther King once said – “The arc of the moral universe is long, but it bends toward justice.” I believe that. The international community believes that. And right now, we are bearing witness to the Iranian peoples’ belief in that truth, and we will continue to bear witness.

Update (AP): An ominous rumor from Tehran Bureau: “good source: Hospital close to the scene in Tehran: 30-40 dead thus far as of 11pm and 200 injured. Police taking names of incoming injured.”

Update (AP): I linked the Facebook video of the young woman being murdered by the Basij earlier but it deserves wide dissemination so I’m giving you the embeddable LiveLeak version too. Forward the link around.

Update (AP): More Twitter reports trickling in about acid or some other sort of corrosive agent being dropped on protesters. And there’s a hot rumor that the Canadian embassy in Tehran has its gates closed to the injured, even as many other embassies have theirs opened. Can anyone confirm/deny?

Update (AP): It’s raining rocks on the streets of Tehran.

Update (AP): Reuel Marc Gerecht tries to answer the million-dollar question: Why would Khamenei risk his supreme authority to fix the election for a disposable goon like Ahmadinejad?

Khamenei, who worked with and struggled against Mousavi for a decade, knows the former prime minister politically as well as anyone. The supreme leader knows that what Mousavi lacks in charisma he has always made up in doggedness…

Khamenei acted so crudely and rashly on June 12 because he’d already seen this movie. What’s happening in Iran now is all about democracy, about the contradictory and chaotic bedfellows that it makes, about the questioning of authority and the personal curiosity that it unleashes. Khamenei knows what George H.W. Bush’s “realist” national security adviser Brent Scowcroft surely knows, too: Democracy in Iran implies regime change. Where Iranians in the 1990s could try to play games with themselves–be in favor of greater democracy but refrain from saying publicly that the current government was illegitimate–this fiction is no longer possible. Khamenei has forced Mousavi and, more important, the people behind him into opposition to himself and the political system he leads. Unless Mousavi gives up, and thereby deflates the millions who’ve gathered around him, a permanent opposition to Khamenei and his constitutionally ordained supremacy has now formed. Like it or not, Mousavi has become the new Khatami–except this time the opposition is stronger and led by a man of considerable intestinal fortitude.

I don’t get it. If Mousavi’s famous for his perseverance, the last thing you’d want to do is antagonize him and his youth movement by defrauding him. It’s practically begging for an uprising. The smart move would be to placate him by bringing him into the regime and then compromising with him on some basic reforms; that, at least, would keep the regime in place. It makes more sense to me to think that Khamenei feared opposing Ahmadinejad because he’s been such a generous patron to the Revolutionary Guard. If Mousavi won and Khamenei endorsed it, the Guard might stage a coup to protect the gravy train they’ve been riding for the past four years. That’s my theory and I’m sticking to it.

Update (AP): Have we already reached the point in the crackdown where negotiating with Iran is unthinkable? I know The One has his heart set on it, but the point’s going to come — if it hasn’t already — where the regime behaves so monstrously that he simply can’t afford a photo op with them. As a thought experiment, imagine that the tanks roll tomorrow and then Khamenei turns around on Monday and offers to give up the nuclear program in exchange for the lifting of all sanctions and full diplomatic recognition. Can Obama make that deal now, knowing that it would legitimize these monsters?

Update (AP): Uh oh: The latest Twitter rumor claims there’s a tank in Azadi Square.

Update (AP): CBS reporter Mark Knoller reports that the president decided today of all days would be a good time for a leisurely trip to the ice-cream parlor. Quoth Jim Treacher: “Imagine if Bush went on an ice cream run during something like this. He’d be ‘Worst Person in the World’ every day forever.” Any lefties care to dispute that, especially in light of the longstanding faux outrage over this clip?

Update (AP): The latest unverified/rumored death toll is 150. In other news, Obama ordered a small cup of vanilla.

Update (AP): If Gutfeld’s this pissed about the skateboarding photo op, wait until he hears about the ice cream trip.

Am I an old fart or am I right to be pissed that some jackass is skateboarding down the halls of the White House while all this Iranian shit is going down?…

Right now, people are risking their lives for the glimmer of freedom, and Tony Hawk is in the White House tweeting about Frosted Flakes.

Update (AP): I’m skeptical that Mousavi would send a letter to Obama without publicizing it, but for what it’s worth, Michael Ledeen says he’s got a copy. Excerpt:

In the name of the Iranian people, we want you to know that when you recently made the statement “Achmadinejad or Mousavi? Two of a kind,” we consider this as a grave and deep insult, not just to Mr. Mousavi but especially against the judgment of the Iranian people, against our moral conviction and intelligence, especially those of the young generation that comprises a population of 31 million.

It is a specially grave insult for those who are now fighting for democracy and freedom, and an unwarranted gift and even praise for Mr. Khamenei, whose security forces are now killing peaceful Iranians in the streets of every major city in the country.

Update (AP): If Iranian goons are willing to shoot women dead in the street, I guess it makes sense that they’re willing to drag the wounded from hospitals where they’re being treated. Note that communications from the notorious Evin prison have been cut off, too. I’ve got a nutty hunch that whatever’s going on inside is a bit worse than waterboarding.

Update (AP): CNN is airing YouTube vids of today’s brutality nonstop, which makes me think American public opinion of the regime will soon be so poisonous as to make diplomacy impossible. The One simply won’t be able to justify shaking these cretins’ bloody hands. If that’s so, it means negotiations are dead and a desperate Israeli attack on Iran’s nuclear sites is assured — unless the regime is overthrown. The stakes couldn’t be higher.

Update (AP): I keep waiting for news to break that Hamas or Hezbollah has attacked Israel, as Iran could use a distraction right now to appeal to the protesters’ sympathies. Maybe this week? Southern Iraq would be an even more attractive target, as it would embarrass the U.S. The fact that they haven’t done that may be among the best evidence yet of how weak their influence has become in that part of the country.

Update (AP): Just posted at Mousavi’s Facebook page, feast your eyes on Iranian police rushing a crowd of protesters, unsheathing the batons, and swinging for the fences. The chaos starts a little more than a minute in.

Update (AP): The sounds of terror: Screams in the night as the Basij break into people’s homes.

Update (AP): I’m skeptical, but supposedly this clip shows the good guys getting a measure of revenge by lighting a gas line … that leads straight into a Basij complex in eastern Tehran. Watch for the boom five seconds in.