- at war, or civil war (ukraine, south sudan, iraq)
- with historical conflict with larger neighbours, and reaso to worry about it breaking out again (Pakistan, Israel)
- sitting on enough oil that GDP gets distorted anyway (saudi arabia, Azerbaijan
So yes, US military spending is way out of proportion to the rest of the world.
[0] http://data.worldbank.org/indicator/MS.MIL.XPND.GD.ZS?year_h...
The global share of GDP spent on military (as of 2015) is 2.29%, and most countries are below that (the US having a huge GDP and spending significantly above that drags up the global share); the US's 3.3% is quite high.
America does often not like it when countries other than itself goes to war because it makes it hard to sell American consumer goods there, unless those goods are the weapons of war themselves.
It's not that disproportionate. Most militaries are funded within 2%-6% of GDP. America's economy is just so enormous that the spending seems ridiculous. Yes, there is a lot of waste, a LOT OF WASTE, but it's a small price to pay to feel safe and secure from foreign militaries when one has the benefit of, as the economist put it: "friends to the north and south and fish to the east and west."
The thought that a war could ever occur on our own soil is simply something most Americans don't even contemplate, unless you've spent one too many evenings polishing your favorite firearms and rewatching "Red Dawn."