World peace is an ideal of freedom, peace, and happiness among and within all nations and/or people. World peace is an idea of planetary non-violence by which nations willingly cooperate, either voluntarily or by virtue of a system of governance that prevents warfare. The term is sometimes used to refer to a cessation of all hostility among all individuals. For example, World Peace could be crossing boundaries via human rights, animal rights technology, education, engineering, medicine, diplomats and/or an end to all forms of fighting. Since 1945 the United Nations and the 5 permanent members of the Security Council (the US, Russia, China, France, and the UK) have worked to resolve conflicts without declarations of war. However, the United States and other nations have entered several military conflicts since that time. Even without a declaration of war, the use of military force prevents the realization of World Peace.