It used to be the mindset of the US Army that it would be capable to two Conventional Wars at the same time but that has changed as our force size has been diminished over time and even the dullards at the Pentagon currently have had to admit to themselves that is no longer remotely possible.
If the allegations against Bush/Cheney/Rumsfeld are to be believed....the shift to Iraq resulting in ignoring Afghanistan in the process....then your Military Leaders need to wake up and smell the coffee.
We never really prosecuted Afghanistan like a real War.....sadly for the Troops who gave so much for so long while fighting there.