So the reality is that Obama opposed the Iraq War before he supported it, which was before he opposed it again, with less clarity or passion than his original opposition.
But the President didn't stop there, either, on March 26 in Brussels, when he had already defined the Crimea situation as "a moment of testing for Europe and the United States and for the international order that we have worked for generations to build." With that kind of rhetoric early in the speech, he could have been leading up to a call for war.
Even when he said: "What we will do always is uphold our solemn obligation, our Article 5 duty, to defend the sovereignty and territorial integrity of our allies. And in that promise we will never waver". every NATO member state must step up and carry its share of the burden" -- he still wasn't making a call to war.
But he was making a disingenuous call to support the Ukrainian national government in Kiev as if it was a legitimate government. That bit of Western hypocrisy was needed to obscure the reality that the Kiev government came to power in a wholly undemocratic putsch. And it was a putsch in which many Western hypocrites were quite involved, so best to finesse it.
And a call for something other than war was pretty much the way to go, which the President did: "I believe that for both Ukraine and Russia, a stable peace will come through de-escalation, a direct dialogue between Russia and the government of Ukraine and the international community, monitors who can ensure that the rights of all Ukrainians are protected, a process of constitutional reform within Ukraine and free and fair elections this spring."
Since a "stable peace" actually exists right now (an "unstable peace" is an oxymoron), there's a veiled threat and a veiled promise in the President's deployment of the term, since it suggests that both sides should back off and live with the status quo. In others words, so much for Crimea. You could call it giving Putin the Bush-Cheney treatment, although Putin is getting away with a lot less murder.
But that's not something a President wants to say out loud and clear, and so he soon arrived at the distraction of the Iraq War, which he opposed, supported, opposed, and ended in disarray.
"But even in Iraq, America sought to work within the international system.