Russia can defeat any army in the world on land as long as they can do it quickly. But russia is a very poor country with a fairly small population, and vast territories.
China is and will always be easy to starve to death with nothing more than normal submarines. They know this. Which is why they have ‘stolen’ the south china sea: strategic necessity. China’s only options are economic and nuclear. She may eventually win dominance by economic means, since her market is a monopoly, while the western civilization’s market is fragmented into many pieces. However, if the western civilization’s market united into a monopoly china would return to practical weakness. Remember china remains, and will remain, for a very long time, a poor country per person. It is kind of hard to imagine india and america going to war, we have no reason to. It is more likely that india and china will go to war and india will depend on america.
The threat to america is the unification of germany, eastern europe, and russia, against the united states.
Frankly, as an american, I would prefer that outcome, and that we could have our own national government instead of running an empire at the expense of our peoples.