Posted at 10:52 a.m., moved up...

He's not going to announce a strike, according to tweets on Twitter.

UPDATE: Could Twitter be wrong? It sure sounds like Obama is about to announce a strike against Syria. We can hit Syria whenever we want. We're ready to go—today, tomorrow, next month.

"This attack is an assault on human dignity. It also presents a serious danger to our national security," says Obama. "I have decided the U.S. should take action against Syrian military targets."

UPDATE 2: Wait: Obama is going to ask Congress to vote on a strike—when Congress gets back from its recess on September 9. He's not calling Congress back into session early. So... no strike against Syria will be announced today and none appears to be imminent. And since House Republicans oppose anything Obama supports, and since House Democrats aren't going to line up behind air strikes, I'm thinking Obama isn't going to get approval from Congress. "We should have this debate," says the president. We should. It's a debate the Brits had in Parliament earlier this week and MPs said no to Prime Minister Cameron. I'm thinking Congress will likewise say no.

The president's rationale for a strike: enforcing international treaties against use of chemical weapons. If the international community doesn't punish Syria for using chemical weapons against its own citizens—or if the international community declines to act, if the United States doesn't punish Syria all by our lonesome—the use of chemical weapons will spread, terrorists will get their hands on chemical weapons, international norms, treaties, and institutions will be undermined.

Obama: "Here's my question for every member of Congress and ever member of the global community: What message will we send if a dictator can gas hundreds of children to death in plain sight and pay no price? What's the purpose of the international system that we've built if a prohibition on the use of chemical weapons that has been agreed to by the governments of 98% of the world's people and approved overwhelmingly by the Congress of the United States is not enforced?"

I predict Republicans in Congress and GOP talking heads and Matt Drudge and Peggy Noonan and Tea Party psychopaths will call the president weak—they're probably calling him weak already (can't bear to swing over to Drudge; it's too nice a day)—but they would be calling Obama a tyrant if he had gone ahead and ordered air strikes without consulting Congress.

UPDATE 3: TPM has a handy guide to 30 years worth of military strikes against other nations...

UPDATE 4: Matt From Denver directs us to WaPo's "Syria for Dummies"—totally worth your time.