It's around 3.4% GDP. That puts us in the top 10% or so worldwide, but it's not ridiculously high. It's on a similar level as countries such as Morocco and Colombia, which aren't known for excessive military spending. It's still kind of high for a country with no nearby enemies, but for the most part, US military spending is large because the US economy is large.

It's around 16% of the total federal budget. To be fair about 1/3 of "military spending" is actually Salaries, Medical, Housing and GI/Retirement costs.

It's also the case that none of the CIA, NSA or DHS budgets show up under the military, even though they're performing some of the same functions that would be handled by militaries in other countries.

We also have "black appropriations." So the total of the spending on surveillance and kinetic operations is often unknowable. Add to this the fact the Pentagon has never successfully performed an audit and I think people are right to be suspicious of the topline "fraction of GDP" number.