Dr Alf is correct. The Russian people will be made to bear the brunt of any credit rating agency downgrade, just as people in the UK were when we lost our AAA credit rating courtesy of Moody’s and then the others.
Clearly, the credit rating agencies can damage the Russian economy but this is limited by the fact that the world is now so interconnected that trouble in one place can and does create a knock on effect, as is happening with the Eurozone, which is still failing to deal with its problems.
In the end, it is not possible to simply isolate one country of that size and power and make it pay for its actions, without any consequences for ourselves in the West.
Life is now a series of messy and sometimes unedifying fudges, not something clear cut where we can deliver a solution wearing spotless “white gloves” aloof and untouched from the consequences of our decisions.