The entire international community should tell any aggressor that they cannot annex or take territory from anyone else. If they want more land, possibly they could buy it or negotiate with the sovereign state from which it would come. Military annexation and commandeering of neighboring territory should be absolutely forbidden and the aggressor should be cut off at the shoulder. There is no way that Putin should be allowed to take one square inch of Ukraine, including Crimea. The problem was he was let to get away with it then and now he thought he could do it again. Any neighboring state of his has every reason to be worried that they could be next. Again, the international community must put a stop to annexation of territory... Full stop.