The Iron Dome... Being able to use AI to calculate incoming missiles, computer trajectories and launch intercepting missiles effectively. It might be possible to do some of that, but significantly less effectively.
see Ukraine drone warfare ... there's a lot going on there which is more than just miniaturized motors, etc. a lot is efficient power use of the semiconductors in those drones, the image processors attached to the cameras, etc. that i suspect relies on newer processes
Like person below said, I assume the drone/AI warfare of the present and near future, along with IoT-integrated warfare and sensors and communications, function better and cheaper and faster with modern silicon.
In 2004 Iraq, we had guided missiles, night vision, explosives, satellites. What advantages would 3nm transistors give the enemy in combat?