I wouldn't compare it to wartime spending, though.
I'd put it this way: even the dovish Carter submitted a budget that ultimately raised it to 6% from a post-Vietnam low. And people that post that transcript of Eisenhower talking about the military-industrial complex? Spending was nearly
10% of the GNP at that time.
There's lots of room for argument about defense spending but historically 3-4% is pretty much where we've been since the original post-Cold War Bush cuts back in the 1990's and the economy has more room to absorb that spending than it would have in the past.