So if this is the case (and I don't doubt what you are saying) then that means Russia has decided to turn it's functioning market into something that is no long

So if this is the case (and I don't doubt what you are saying) then that means Russia has decided to turn it's functioning market into something that is no longer a market. Only because we now have a situation where any foreigner holding a Russian security can no longer sell that security. That action has instantly made the security worthless (i.e. value of zero) to the foreigner. So while these actions might stop the price drop in the short term, it will never last only because the market created is no longer reflecting the true value of the security. They are now only being held artificially high because no one can buy and sell them.