One Guess as to what they a swapping US Debt for

Both China and Russia's holdings of US treasury debt have reached their lowest point in over a year, with Russia's holdings down 50% since Oct 2010.

Whilst figures of official gold holdings in China and Russia are opaque at the best of times, one has to assume some, if not most of the proceeds of the sales of US treasuries have found their way into the gold market via open market purchases or in the case of China mostly by direct off take from local mines (China is now the world's largest Gold miner and is either the 1st or 2nd largest importer of gold annually).

Charts from ZeroHedge.com