Russia has a long tradition of "protecting"
"[...]The Soviet Government also cannot view with indifference the fact that the kindred Ukrainian and White Russian people, who live on Polish territory and who are at the mercy of fate, should be left defenceless. In these circumstances, the Soviet Government have directed the High Command of the Red Army to order troops to cross the frontier and to take under their protection the life and property of the population of Western Ukraine and Western White Russia."
People's Commissar for Foreign Affairs of the U.S.S.R. V. Molotov