I am worried they might create an uninhabitable belt on the western borders of Western Ukraine by nuking it with 10-100kT tactical nukes as they don't really care about people of Lviv and around and that would solve also their Polish "friendship" problem. A similar strategy was planned by French in the case of a war with USSR, nuking Poland, Czechoslovakia, Hungary, Romania, so that the USSR army couldn't pass to Western Europe. I think all options are on the table, unfortunately.