This article aims to present the causes of the conflict between Russia and Ukraine and its future evolution scenarios. In addition to Russia and Ukraine, the United States, European Union countries and NATO (North Atlantic Treaty Organization), a Western military alliance, are involved in this conflict. With the end of the Soviet Union in 1989, NATO was expanded to meet the geopolitical interests of the United States. During the Cold War between the States and the Soviet Union, NATO had 16 countries until 1989, attracting in 1997 another 14 countries that were part of the Eastern European socialist system. More recently, Finland and Sweden joined NATO. All of this is part of the strategy of the United States and its European allies to get closer to the borders of Russia, which is considered, along with China, an enemy of Western powers. The facts of life demonstrate that, for centuries, humanity has been faced with conflicts between great powers that are not resolved through diplomatic means but through military means because we live in a world without a world government and without international law that is respected by all countries, especially by the great powers that seek to impose their will on the world level. Without a world government and a world parliament democratically elected by the world's population, as well as without the existence of a world Supreme Court, there is no way for international law to be effectively applied and respected by all countries. It is urgent for humanity to equip itself as urgently as possible with the instruments necessary to build a world of peace.