The article analyzes the participation of post-Soviet republics in NATO peacekeeping operations under the mandate of the UN Security Council. The facts of direct participation of military units of the former Soviet republics in the preservation of peace and stability are stated chronologically. The Ukrainian legislation on the use of national army units outside its own territory is considered. The decisive role of NATO as the main mechanism of implementation of the UN peacekeeping functions is emphasized. The change of the strategy of the Alliance from collective defense to collective security is emphasized. The peacekeeping activities of the Russian Federation on the post-Soviet territory are analyzed.