The obvious answer is to have no nuclear weapons. But everyone will think to themselves "We got rid of our nukes, but if they still have a few then we could be totally totally screwed."
The more feasible way is arms limitation. Let's say you go from having enough nukes to destroy the entire planet to merely having enough to end your opponent's civilization as we know it. But the more alliances means the more enemies or even targets on your own side.
10,000 to 1,000 is relatively easy. 1,000 to 100 is very very hard. <100 will probably never happen :(
The more feasible way is arms limitation. Let's say you go from having enough nukes to destroy the entire planet to merely having enough to end your opponent's civilization as we know it. But the more alliances means the more enemies or even targets on your own side.
10,000 to 1,000 is relatively easy. 1,000 to 100 is very very hard. <100 will probably never happen :(