I think that huge devastating attacks with cruise missiles are on the way out. Patriot systems are getting better and you would have to destroy them for the big missiles to be effective on the stronger countries. I think the best invention for the military would be a perfect espionage device, one that could watch any person without them knowing that they were being watched. Then all enemies of the state would have to be very careful about what they were seen doing because they would have to assume they were being watched at all times. Surprise attacks would be impossible.