Stephen M. Walt wants to cut the defense budget:

National security is obviously important, but the Department of Defense should not be exempt from the sacrifices that we all have to make over the next few years. I'm not talking isolationism or radical disarmament here; just the prudent adjustment of ends and means. A country can't squander more than a trillion dollars in Iraq and Afghanistan, mismanage a lot of other aspects of its foreign policy, and then suffer a financial meltdown without paying a price. And one of the ways we pay that price is by scaling back our ambitions and investing the remaining resources as prudently as we can.

Obama may have already begun in Afghanistan.