I have not yet watched the speech, but I have read the text and wanted to put some thought down before my impressions are polluted by contact with other people’s commentary.
You can think of this speech as containing two arguments. One is “yes committing the United States to defeating the Taliban is a good idea” and the other is “I have a workable plan for doing it.” In general, I think the case for the first proposition is weak, but I think war opponents have tended to understate the feasibility of the Obama/McChrystal kind of plan. The speech itself, however, was oddly weak on the feasibility point and instead lead into the weird kinda sorta promise to start winding the war down in 2011 which struck me as a promise vague enough to not reassure the left while also being concrete enough to set the right-wing piranhas in motion.
At the intersection of these two arguments is the idea of “no blank check” for Hamid Karzai. How, one naturally wonders, is the check not blank if the President of the United States has defined the mission as serving a vital American interest? If you made the case that the mission is a good idea differently—if you just said we’re obligated to the Afghan people and government to give it a try—then your check has real limits. We’re obligated, but they’re obligated too, and if they don’t meet their obligations we can meet ours so we’ll have to walk away. But that’s not what he said. What he said was “I make this decision because I am convinced that our security is at stake in Afghanistan and Pakistan . . . [w]e must keep the pressure on al Qaeda, and to do that, we must increase the stability and capacity of our partners in the region.” Insofar as that’s true, then it’s true completely independently of how we feel about the Afghan government, so Afghan government actions have a limited influence on our policy, so whatever checks we write to them are pretty much blank.
At any rate, this promise that “[a]fter 18 months, our troops will begin to come home” doesn’t strike me as the kind of thing you can take to the bank, but I hope it comes true and I hope it’s not a promise they would make unless they’re reasonably confident they can fulfill it.