Challenges for Defense

The struggle to pay for war, new equipment, and social programs, from National Defense Mag.:

We have seen defense budgets grow consistently since 9/11. This was a necessary move to support expanding military commitments in Afghanistan and Iraq. But it is becoming increasingly clear that the spending will have to level off at some point, if the nation is to get its financial house in order.
At the same time, the United States will need to somehow find a way to keep its military forces from “breaking,” as a result of repeated deployments, depleted stocks and worn-out equipment.

Though the US is spending less than 4% of its economy on defense, a huge chunk is going to non-military spending, causing a huge dent in the budget. And its getting worse:

Based on 2006 projections, by 2040 the entire U.S. federal budget barely will be enough to cover just Medicare and Social Security.