He essentially had three choices. 1. Pull out of Afghanistan and let the Taliban take over again, Al Qeada set up training camps again and completely destroy our credibility with every ally we have, as well as encourage countries like N Korea and Iran to pursue aggressive policies. 2. Hold the line and allow the situation to continue to erode and put the troops we have there at further risk. 3. Send in reinforcements to punch back at the Taliban and hold ground until the Afghan government can take over the mess.

The exit strategy forces the Afghans to get their shit together while the surge allows a more aggressive series of actions to hurt the Taliban. Sure, the Taliban will wait us out, but while they are waiting hopefully the Afghan government gets its shit together and makes it much harder for them to come back once we do leave.

As TB said Obama made it clear during the campaign he consider Afghanistan the real problem since that is where the guys who attacked us laid their plans. Since taking office Obama has now doubled the size of the force there.