This report from Bloomberg citing unnamed people familiar:
U.S. and U.K. are weighing additional penalties against Russia over the use of chemical weapons
- Options canvassed include sanctions against oligarchs through to what Bloomberg refer to as "the extreme step of targeting the nation's sovereign debt"
Yes, that would be at the extreme end of the spectrum.
Bloomberg adds:
- One trigger for additional steps would be if Russia continues to stonewall an investigation into Navalny's poisoning, one person said.
Here is the link for further information.