Apologies for a blogging lapse on my part. I should have written about this sooner. People are paying attention to the demonstrations in Iran, Yemen, and even Libya(!), but I’d bet that the big flashpoint in the region will come in Bahrain. It’s hugely significant for two reasons: It’s the home of the Fifth Fleet, which is understandably nervous about what instability could mean for America’s strategic options, and it sits squarely on the political fault line between Saudi Arabia and and Iran. The king is a Sunni and a Saudi client but the population is 70 percent Shiite, making Bahrain the only country in the Middle East besides Iran and Iraq with a Shiite majority. The fear, of course, is that if the king is toppled, not only will Bahrain become an Iranian client state but reform fever might finally catch on next door in the kingdom and threaten the Saudis themselves.

Hence the odds of a flashpoint: Even if Bahrain’s king is willing to agree to constitutional changes, the Saudis might intervene on his behalf and try to crush the demonstrations to create an “autocracy firewall” and send a message to dissidents back home. There have already been three full days of protests, replete with Bahraini police temporarily withdrawing from the streets to give way to demonstrators, so if a crackdown’s coming, it’s probably coming soon. And in fact, according to this story at the Times, it might have already begun. Given the obvious U.S. interest in retaining Bahrain as a base, protecting Saudi Arabia from radical populism, and limiting Iran’s influence in the region (not to mention the $10 billion in mutual funds parked there), how forlorn do you think Obama and Hillary will be if Saudi tanks roll?

Hundreds of riot police surrounded the nation’s symbolic center, Pearl Square, in the early morning Thursday, raining tear gas and percussion grenades on thousands of demonstrators who had poured into the square all day Wednesday to challenge the country’s absolute monarchy…

Witnesses, some of them vomiting from the gas, said they had no warning the police were going to crack down on their peaceful protest before rows of police vehicles with blue flashing lights began to circle the area…

The protest was started early in the week by young people, but by midday on Wednesday political leaders had decided the nation had reached a tipping point and that they would try to leverage what appeared to have become an unstoppable political force.

The leaders of the largest Shiite political party, Al Wefaq, announced that they would not return to Parliament until King Hamad bin Isa al-Khalifa, a Sunni, agreed to transform the nation into a constitutional democracy with an elected government. Though they had no formal authority over the protesters, the political leaders said they were confident that the community would heed their calls to end the protests if their fundamental demands were met.

This is, as Biden would say, a big effing deal. ABC is reporting that one of its reporters in the square was beaten by security forces during the crackdown and an opposition leader tells CNN that at least one protester is dead. That’s also a big effing deal, as it was the killing of two demonstrators a few days ago by Bahraini security that catalyzed the protests in the first place. (Just yesterday, the king took the unusual step of apologizing on television.) This morning, protesters were vowing to put at least 50,000 people in the square on Saturday, a hefty number in a country of just 1.2 million people. What happens now? Do the demonstrations end out of fear of an even more violent crackdown to come or do people turn out en masse tomorrow in a “day of rage,” which would force the Saudis to decide how far they’re willing to go? And if they decide to go all the way, what happens to their relationship with the White House?

Whatever happens, tomorrow’s a big day. As Michael Totten said of the mullahs, so too with the Saudis: Realistically, there’s nowhere to run.