Are U.S. Military Expenditures a Public Good for the Rest of the World?

My first thought on whether the U.S. is"stingy" in allocating aid to the victims of the tsunami, is to declare that I prefer for this government, indeed any government, to be as stingy as possible (and the appropriation of privately owned resources correspondingly lower) and for private individuals to be as generous as they choose to be when disaster strikes. My second thought is that as long as the U.S. has armed forces around the world, I'd rather they take part in rescue efforts than invading and occupying other nations.

I've skimmed some of the debate (which I don't find particularly interesting) and come across a post by Daniel W. Drezner here. Drezner argues that"One could make the case that comparing large economies with Scandanavia or the Benelux states is unfair, because the bigger economies have other public goods functions to fulfill" and cites an article by Bruce Bartlett. Bartlett declares that "U.S. Falsely Charged with Being 'Stingy' on Foreign Aid" and makes some good points about how private individuals in America contribute to world prosperity. That said, I found the argument cited by Drezner thoroughly unsatisfactory. Bartlett states:"The first thing one notices when looking at the big foreign aid contributors is that they all spend very little on national defense. According to the Stockholm International Peace Research Institute, in 2002, The Netherlands spent just 1.6 percent of its gross domestic product on defense. Norway spent 2.1 percent, Switzerland spent 1.1 percent, and Ireland spent a piddling 0.7 percent. By contrast, the U.S. spent 3.4 percent--and this was before the Iraq war. It's easy to be generous with foreign aid when another country is essentially providing your defense for free." But is the U.S. really providing for their defense? And defense against what? Indeed, aren't U.S. policies (invading and occupying Iraq as the most egregious example) actually destabilizing the world and endangering the lives of the citizens of these nations, particularly when they travel abroad?