What impact would sanctions on Russian sovereign debt have?

A bill presented in the US Senate yesterday has raised the threat of US sanctions on Russian sovereign debt. Were the bill to pass, we think it might plausibly add a premium of about 50-100bp to the yields of newly issued bonds. There could be a more general rise in Russia’s risk premium, pushing yields up on all debt and causing the ruble to weaken, although our sense is that this effect should be modest.