@quixoticgeek Another aspect is that Google employs quite a number of people in Europe. So a sudden full block of say all of Europe would be highly disruptive for Google too.
But even then, Internet traffic could still transit via third-party countries, using proxys, VPNs, etc. Sure, user accounts could be suspended, which would be disruptive but eventually new ones could be created. Unless the US blocks itself from the whole Internet at the physical level, or convinces all the third-party countries to adopt the same blocade (which I highly doubt as breaking NATO would weaken the US in the world order), I don't think there's really a way to ban a specific set of countries.