I read an article a few years ago (Popular Science, I think) that said the US government runs a complex computer simulation of war every ten years to assess their position versus the world.
There was concern after the last simulation that US was falling back as the leader more rapidly than anticipated.
China was the greatest concern.
In the previous simulation (~2000), a conflict with China was to last around 24 hours and only result in around <5% damage to forces.
In the last simulation (~2010), the risk had already grown to a 30 day conflict with ~20% damage to forces.
My memory is pretty certain on those time frames, but the damage numbers are a bit more hazy to me.
There was concern after the last simulation that US was falling back as the leader more rapidly than anticipated.
China was the greatest concern.
In the previous simulation (~2000), a conflict with China was to last around 24 hours and only result in around <5% damage to forces.
In the last simulation (~2010), the risk had already grown to a 30 day conflict with ~20% damage to forces.
My memory is pretty certain on those time frames, but the damage numbers are a bit more hazy to me.