Ultimately, as we move towards a single-payer system, I suspect defense spending will need to shrink to European levels. We’re still protected by two oceans and bordered by friendly (and weak) neighbors. World events may generate many more exciting headlines as we begin abrogating defense treaties after an initial spasm of hyperactivity. And I think it’s long overdue - the world has been sucking at the teat of American military welfare spending for far too long. It’s time they spend their own money defending themselves from their enemies. Europe wasn’t economically weaker than the US before WWII occurred. Individual countries merely decided that there is no such thing as an enemy - just friends you haven’t met.
In the 20th Century we had major periods of disarmament also. The Periods were right before World Wars 1 and II. When we abandon our military strength, the tyrants of the world take note. We are inviting full scale war IMHO.