Environmental damage is proportional to the population density. The overpopulation leads to a shortage of fresh water and food in many regions. Smoldering international conflicts provide motives for the population growth. 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 sovereignty and national defense. Several regions with a relative overpopulation, actual or potential conflicts are discussed here. Today, when common interests of the humankind are becoming obvious, the introduction of new moral principles is needed. One of such principles is that a birth rate of an ethnic minority should not be higher than that of the main nation of a country. Social consequences of gender imbalance must be borne mainly by those population groups, where sex-selective abortions are practiced. Recognition of these principles can become a basis for the international trust and cooperation.