The conflict in Ukraine and ensuing energetic crisis has hindered environmental policies in Europe and elsewhere. The war itself has severe environmental implications. The conflict between two major agricultural countries has negative impact on the global food supply. As food prices rise, some nations are likely to cope by converting forests and grasslands to fields. International tensions and conflicts are among reasons to boost childbearing in Russia and some other countries. There are inter-ethnic differences in the birthrate within Russia and worldwide. The necessity of birth control has been obfuscated by conflicting national and global interests, the population growth being regarded as a tool helping to the national sovereignty and defense. The pro-natalist policy is counterproductive in view of the global overpopulation. The ecological damage is generally proportional to the population density. The demographic growth contributes to the scarcity of energy and food in many regions. The energy could be supplied by nuclear power plants (NPPs). Well-managed NPPs pose less of a risk than those running on fossil fuels. The nuclear facilities practically do not emit greenhouse gases. Obviously, a lasting peace is needed, since NPPs are potential targets. By analogy with the Chernobyl accident, the war damage and shutdown of the Zaporozhie NPP (the largest NPP in Europe) will enhance demands for fossil fuels. In the past, the overpopulation was counteracted by wars, pestilence and famine. Today, scientifically based humane methods can be used to regulate the population size taking account of ecological and economical conditions in different regions. Large projects could be accomplished to improve the quality of life all over the world: irrigation systems, nuclear and other energy sources instead of fossil fuels. Hydroelectric power plants can be built on large rivers to produce hydrogen as eco-friendly energy carrier. Such projects would create many jobs, being a reasonable alternative to hostilities and excessive military expenditures. Not only durable peace but also mutual trust is required for that. Ukraine should become a testing ground for the international trust and cooperation.