Let’s get straight to the point. Anything beyond 30 years from now is not too interesting for us. Long-term investments are important, but we can’t control the outcome. Usually, I’d rather make it 5-10 years, but the world is rather balanced now and there’s not much we can do unless we assume our enemies are stupid. Military-wise, there are only 3 options today: physics, chemistry and biology.
Physically, it is still very difficult to build a space shield to defend ourselves against a nuclear strike. Let’s give ourselves 20-30 years on this one. There’s not much else to be said. Mutual annihilation is great, but it’s more like psychological warfare.
Chemical weaponry will yield the greatest pain on individuals, but the payload of long-range missiles may be disappointing. Again, pain is not an objective.
Biology seems to come to the rescue, but again, viruses may spread worldwide so cures must be made in advance. This means that it will be a spy game. Either way, nothing is as sure as a nuclear strike, completely painless.
Hurting the innocent through drugs is way below our means. We are humans and not animals.
If China really wants to gain international influence, they have to learn Military 101. Speed is everything!