You need to define what Europe means to you, and list which countries you include, since Europe as itself is not a defined concept, and geographers have debated for a while which countries should be considered European or not. It seems you may be referring to the political entity European Union, but it’s unclear.

If you rely on the EU, an edge case question I’d have would be whether any travel from Putin in the EU under diplomatic protection would count? For example, travelling to the International Justice Court in The Hague/Netherlands (not that I think likely he’d go there).

@Mattfr Sorry if that's not clear - I assumed listing the countries I exclude is enough. I mean not the EU but geographic Europe except for the countries mentioned in the description.

Visiting under diplomatic protection would count so long it's voluntary.

@PS Ukraine is being considered for adhesion to the EU, and claims the eastern territories to still be under its jurisdiction. So would a visit of Putin in Crimea for instance count as a voluntary visit in a European country? Same for a visit in Transnistria (claimed by Moldova). My guess is no per your description, but I hope this can illustrate the current ambiguity of this market.

@Mattfr Since the description explicitly excludes Russia and Ukraine, I thought it's quite unambiguous that Crimea does not count - what ambiguity do you see?

Transnistria is a good point, thanks for bringing it up. I think it wouldn't count, will update the description accordingly.