Pretty obvious to me that China and USA are now engaged in a cold war, and must prop up their economies by any means necessary to preserve their preeminent statuses. One stumble will see them at the mercy of their opponent. This is about prestige, its about projecting power.
And on an elemental level, its about preserving the status quo and preventing societal breakdown. Another crash of similar (or greater) impact to the GFC, and you'll see more than just a temporary 'Occupy' movement. You'll see something more revolutionary in nature I am sure.
To that end, both countries are using their central banks to carry out undeclared bail-outs & 'making whole' - and the term always used is 'maintaining liquidity'. And this 'liquidity' is coming from 'reserves' = thin air.
