While tossing out super expensive weapon systems by the bushel basket, programs that collectively the US has already spent billions on. The U.S. is also testing things like drone swarms, for example pods full of killer drones that get dropped from fight planes near battle areas. We'll be seeing (more) assassinations by drone, terrorist attacks by drone etc. etc soon as well. It's only a matter of time.
Major props to James Cameron for absolutely nailing it 40 years ago, not sure about the time travel piece, but the rest is on a screaming train to reality.
The most armed conflict in the world since the end of World War II - The Biden Years
