Ugh math
So at 37% of 1.6T, your source has the USA spending 592B.
To make that 25% of world expenditure, we're down to 360B spend on a world expenditure of 1.44T
This would be a 39% reduction in military spend. So the USA would still be below India, Russia and SA in terms of % of GDP spent for military and on par with China.
That 232B dollars is almost enough to completely defund the Navy, so for that money we have the ability to put aircraft carriers in multiple regional hot spots, such as Taiwan and the Persian Gulf.
We want the Navy and the ability to project force, so maybe we end all ISIS activities and Overseas fundings and recoup
74 Billion. Only 158 billion more to cut. The total Army budget is 194B, so we could reduce to 1/6 of the size. Probably not the answer we want. Air Force is 134B, we could just rely on Naval planes...
If just want to cut evenly, there are about 1.32M active duty across all 4 branches, so we could kick 330K active duty folks out of service.
I'd rather keep our volunteer army and look for efficiencies in the entitlement programs that are 4X the above spend.
ETA: I actually had world spend rising a bit as well. If it's a pure drop, we're down to a USA spend of 337B on a global spend of 1.345T and we can eliminate the entire nuclear triad as well.