You guys read the speech. If not, read the speech.
"Our resolve is unwavering." But, perhaps, only for the next 18 months.
Seems a strange message. And it is. But it may not be unsound.
(Quick summary: 30,000 additional troops, some begging for 5,000 more from NATO, will take a crack at the Taliban while other troops, particularly from NATO, train Afghan forces at absolutely breakneck speeds. Then, 18 months from now, we begin the drawdown.)
This looks quite a bit like the surge strategy in Iraq. And it is. General Petraeus, now in charge of CENTCOM, is probably relatively satisfied. McChrystal certainly is.
The major criticisms from the left are pretty simple--this is a waste of life, of money, we should be leaving. I think the counter-argument here is that there are a few serious points at stake: the first was brought up by the President. There is a serious security risk here. Certainly more than there was in Iraq. And certainly, this is something that we should weigh on its own as a benefit against the cost of the next 18 months, rather than succumbing to the tragedy of sunk costs. The second point is that the odds of winning are probably higher than the left probably thinks. Like it or not, Petraeus, Gates, and Bush showed that "doubling down" in a region has the potential to break the fighting will of folks that have spent the past many years slowly grinding and dying in the mountains to eek out momentum. Afghanistan will be harder than Iraq, due largely to an even-more-dysfunctional central government (and much less centralized society), but it can be done. Third, the cost of losing can go beyond simple security in the medium-term. Victory and defeat can significantly affect the relationships between the United States and other significant powers (Iran, Russia, etc); Vietnam and Afghanistan are both excellent examples. When the US lost Vietnam, its security was not threatened by Vietnam, but the Soviet Union gained a long momentum (as the US wallowed in relative misery and indecisiveness), and the momentum switched after the Soviet Union lost Afghanistan. So I think, as a whole, there is a lot to gain, and a decent chance to get it.
The criticism from the right is, as far as I can tell, centered around "sending the wrong message," as Senator McCain said. The worry, in essence, is that the US is not able to project the will necessary to break the will of the Taliban--they may simply spend the next 18 months hiding in wait, knowing the exact date at which they should spring forth to take down the Afghani government. It is not an entirely illegitimate claim. But if the Taliban does actually take an 18-month break (or relative break) from the fight against ISAF, then ISAF will have two luxuries: one, it will get to spend its massive resources in building up the Afghan Army and government (likely, the Army will have the bulk of the legitimacy of government forces, like in Iraq for some time). Two, it will allow the US to get aggressive and claim territory, hunt bad guys, etc, rather than play guard duty. Every force likes being on the offensive, and the Taliban will have to choose between actively seeking engagement with NATO troops or hoping that they can hide and be just disruptive enough to not give ISAF the luxury of relaxing and building.
Additionally, it will instill some urgency (and, frankly, panic) in the Karzai government. For all his corruption, Karzai is committed to beating the Taliban and holding onto his power base--he won't achieve his own objectives by sitting back and hoping. Knowing that the US commitment (and thus the NATO commitment) has a time limit is likely to motivate him to get his government in good enough shape to keep it together on its own, rather than free-ride off US and NATO efforts.
All in all, there is a trade-off between the message to the Afghan government and the message to the Taliban, but I think the trade-off is being managed pretty well. Furthermore, the trade-off management might actually make enough Republicans and moderate Democrats happy enough that he'll get the requisition he needs to pull it off.
My confidence here isn't quite as high as it was with the Iraqi surge, but it's probably about the best bet the US has right not to pull a win in Afghanistan (even if, yes, "win" was not a word Obama used. Deal with it.) and walk home with not only a safer Middle East, but a much-inflated geopolitical position compared to 2004.