Obama decides 1) to strike Syria and 2) to ask Congress to debate and vote on the question

While he did not go as far as we would have liked, that is to refer the evidence of Assad's alleged use of chemical weapons to the International Criminal Court for their assessment, potential indictment and prosecution of Assad, he did nevertheless bend the arc of American history in the direction of justice, reflection and public debate.
The Congress will debate and vote on the president's recommendation to conduct a military assault on Syria, as an focused attempt to deter others from similar deployment of such outlawed weapons.
This is both an historic and wise decision on the president's part.
He has been blocked for years by this Congress, whose legacy can be summed in one word: "No!"
Furthermore, at least since President Reagan, the White House occupant has conducted "airstrikes" without seeking the approval, or consent of Congress. That arc of American history has been bent in the direction favouring a collaborative decision. And the president, conscious of the dangers implicit his own political high-wire act, to go alone without seeking Congress' voice, has now punted the "ball" into Congress' court.
The actual vote outcome is anything but predictable.
What is not in doubt is that, if the Congress does not and cannot reach a decision to authorize military action, then the President will be able to hang their decision around their neck, and not exclusively around his own. What is also clear is that, while a "time-out" is in effect, the streets of cities around the world will be filled with protesters opposed to any American military action in Syria.
"Hands off Syria" has already become the battle-cry of those protesters on more than one continent, since the Obama announcement earlier today.
Surely, also some member(s) of Congress will actually raise the issue of the United States' failure to sign the treaty establishing the International Criminal Court, where this matter can be prosecuted.
If not some member(s) of Congress, then more than a few news outlets, in more than one or two world capitals will be able to have at that argument.
In any case, Obama will proceed to Sweden and then to Russia for the G20 summit, without having Tomahawk missiles raining down on the chemical deployment systems in Syria, or should the targets not be as surgical and as accurate as the U.S. military would like, on the actual storage depots of those weapons, thereby exploding them and devastating more Syrian in the process.
Even Obama and Putin will have the "unofficial" opportunity to speak privately, although Obama has ruled out any private meeting following the Snowden reception by Russia, for one year.
Anyone who thinks what happens in one capital of the world does not impact other capitals need only examine the impact of the parliamentary vote in the United Kingdom where the Labour Party defeated a motion put forward by the Cameron government supporting military action in alliance with the U.S, in Syria....that surely has had a profound impact on the Obama decision today.
And, while the French and the Turkish governments are still "on side" the rest of the world will now wait, hoping that this hiatus from military action by the U.S. will provide needed oxygen for the seeds of a negotiated settlement of the Syrian tragedy to take root.