Yes, Greenwald is correct about the withdrawal deadline established during the Bush administration.
But it's a valid and honest political boast to say the Iraq occupation/war ended on the president's watch, and there is political upside in saying so.
Anyone who follows the news and the White House press briefings knows the history behind what's going on with the end of the war, and why it's happening: the Status of Forces Agreement ratified by the Iraqi Parliament in late 2008. Many of us also grasp the idea that the military could have exploited loopholes in the agreement and remained in Iraq longer despite the SOFA. I assure you, President McCain and Vice President Palin would have. (And, by way of a reminder, both Hillary Clinton and John Edwards voted to invade in the first place. We can't reasonably guess how they would have handled these delicate wranglings with the Iraqi government, but we do know their respective records on the issue.)
We also know that there was significant pressure on the president from members of his own administration to remain in Iraq into 2012 -- as well as pressure from the Iraqi government to stick to the terms of the SOFA. He ultimately decided to honor the agreement. No one, including Greenwald is capable of reading the president's mind to determine which side he supported. Was President Obama really determined to stay or did he disagree with his Defense Department's desire to linger? I have no idea. Neither does Glenn. History and political reality dictates that a presidential administration doesn't always operate in lockstep and leaks occur for a variety of reasons -- sometimes to float ideas, and other times to test public reaction, and other times, leaks are genuine. It's not always easy to know what to believe until a final decision is reached and details are revealed post-administration.
What we know is that the president erred on the side of Iraqi government pressure and is honoring the SOFA terms. Fact. So whether Leon Panetta wanted X-thousands of troops to stay into 2012 isn't as important as the outcome: the administration honored the terms and the troops are leaving.
So the president promised to end the war by the end of 2011 and bring the troops home. And he's delivering on that promise and it's happening on his watch. This is the reality of how it went down.