Quote from IShopAtPublix:
The country does not exist to serve the military, the military serves the country. There are bigger issues here than sending 40000 troops to the country. The generals don't understand the "bigger picture" The financial impact, the geopolitical concerns, the political realities, etc.
I'd be willing to wager that a West Point graduate, military fellow at Harvard and the CFR who has served and lived all over the world is plenty aware of the "bigger picture", at least as much as someone's whose actual foreign policy experience is limited to one term in the US Senate.