defense spending globally

Matthew Yglesias » Home Page: "Cato’s Will Wilkinson and Joseph Heath from the University of Toronto agree that America’s massive defense spending is, in effect, subsidizing the national defense of other countries and both agree that it’s perverse that American conservatives like this. As they say, the right would be none-too-keen on the idea of the United States paying for Italians’ health care, so why should they like paying for Italians’ defense?"

If the US cut defense spending, would Italy or Canada increase their defense spending?
Which is worse, spending tax dollars on a bridge to nowhere or spending money on extra nuclear weapons that are not needed for deterrence?