Features of armed conflicts at the beginning of the 21st century are discussed through the prism of the theory of asymmetric conflict. Within the framework of this theory, basic and accompanying asymmetries are distinguished, which determine the reasons for the political, rather than military, defeat of developed countries in wars against relatively weak opponents. At the beginning of the 21st century, most armed conflicts have pronounced signs of multiple asymmetries that affect the course and outcome of conflicts. On the basis of the theory, several important aspects can be distinguished that should be taken into account by the military and politicians when planning and conducting military operations. Among them are the legitimacy of military operations from the point of view of international law, neutralization of antiwar sentiments, minimization of losses of military personnel, and ensuring the safety of the population in the war zone. Foreign analytics is characterized by a focus on the reasons for the failures of the United States and other Western countries in military operations in Afghanistan, Iraq, Libya, and Syria. Among the reasons for the failures are a lack of understanding of the culture and characteristics of the countries where hostilities are conducted, the regime of occupation, and attempts at nation-building. Some foreign experts note that the Russian Federation is much more successful in participating in asymmetric conflicts of the 21st century. Among Russian military experts, there is a noticeable interest in developing an "asymmetric war" strategy in the framework of the geopolitical confrontation with the countries of the West. The tendency toward developing noncontact methods of warfare and the involvement of private military companies and toward neutralizing antiwar sentiments and minimizing losses of military personnel has a universal character. At the same time, the problem of the nonselectivity of such methods of warfare and their compliance with international law is becoming more and more acute. The theory of asymmetric conflict is a theory of international relations, the main assumptions of which are useful for politicians and the military to consider when deciding on the start of hostilities and the possibility of achieving political goals by military means, and not just for finding victorious strategies in asymmetric conflicts.