Is Putin afraid of US/EU sanctions?
Yes, I think so - otherwise why has he not already had a full invasion?
That being said, I don’t think we can expect Putin to respond or act in a rational manner.
That doesn’t mean that we won’t make it exceptionally painful for him. The cancelling of the pipeline by Germany this morning was swift and rather unexpected and might cause him a bit of pause of further escalation. Certainly the financial sanctions we have lined up will be crushing for Russia.
He might have to feel an exponential amount of pain to change course.