That's ridiculously stretched. Russia is huge. Plenty of choice of "where you've been to". And you absolutely don't have to answer anything about where you've been to in Russia, because it's actually not their fucking business. Worst they can do is not let you into Ukraine. Surely, theoretically they can illegally arrest you, and torture you, and whatever, but doing that to a USA citizen (or whoever you are) on a basis of slight suspicion you could've been in Crimea or some other territory they consider theirs inside of Russia, well, that's risking way more than you do.