If you look at the history of the world there was an apparent (and counter intuitive) acceleration in the rate at which borders and governments were shifting, largely due to war and revolutions. Then we hit about 1945 and suddenly - it all but stopped. The only very large change being the fall of the Soviet Union, which did not involve direct war nor even revolution.
Nukes have made war between major powers a thing of the past, until they can be contained. 'Modern' nukes make Hiroshima and Nagasaki look like a joke. The 'Tsar Bomba' [1] is a nuclear weapon that was tested by Russia in 1961. Its yield, which was not at full capability, was more than three thousand times as powerful as Little Boy [2], the nuke that practically destroyed Hiroshima. You can't win wars against WMD.
A single missile that is failed to be detected or intercepted and you're looking at fatalities in the tens of millions. And there are thousands of these weapons operational and ready to fire today. Russia has even been developing a nuclear torpedo that's designed to create an artificial tsunami that would produce a devastating radioactive wave greater than 500 meters in height that would annihilate a target. The reason for a nuclear torpedo is to bypass all conventional anti-missile ballistic/laser/etc technology.
In my opinion the issue is relatively simple. If China's growth and development continues at even a fraction of its current pace they're going to become the most dominant nation in the world. This will change the world in unimaginable ways. The current powers on top are pretty happy with the status quo, and aren't ready to say goodnight just yet. Traditional war is not an option so I expect we're going to see a continuing increase in aggression on the two new fronts of war: economic and information.
[1] - https://en.wikipedia.org/wiki/Tsar_Bomba
[2] - https://en.wikipedia.org/wiki/Little_Boy