Ukraine

Gold is nothing if not something that can be easily and efficiently smuggled. The gold can be simply re-cast into generic gold bars or minted into back-dated Russian bullion coins. Just one passenger car can smuggle millions of dollars of gold across the border while attracting little scrutiny. From then, it can simply be easily sold to bullion dealers. Then the cash can be ferried back across the border or deposited in accounts at Kremlin-friendly banks.

If you have a network of agents doing this, you could probably offload thousands of ounces worth millions of dollars a month.

There's also the simple option of sending it all to a shady Chinese commodities exchange.