For instance, the US maintains about 1/2 of active aircraft carriers.
https://en.wikipedia.org/wiki/List_of_aircraft_carriers_in_s...
I guess the strategic problems with aircraft carriers vs missiles make them a less compelling example of capabilities, but they are a nice illustration of the spending gap.
Later: 1/2 maybe isn't the best choice for a number there, as it includes some smaller carriers that mostly support VTOL craft. On the other side of it, the US super carriers carry a lot more planes. If the next generation planes come through, the smaller US carriers do end up comparing reasonably well to the other small carriers.
At least the military budget is a) constitutional b) a reasonable expenditure for a government (as opposed to a mutual-aid society).
When us younger Americans start drawing our Social Security, it'll be that era's young whose pennies we're drawing.
Social security isn't "you pay in, you get back out what you put in" it's "you pay in for today's olds, and when you're old, young people pay in for you".
EDIT: I believe using percent of GDP is a poor measure.
Give me a percentage of your take home pay. Let me burn it in front of you in a dumpster. No worries! Its a small part of your take home pay!