The North Atlantic Treaty Organization (OTAN), known as NATO in English, is a military alliance established in 1949. Its primary purpose is to ensure collective defense among its member countries, meaning that an attack on one member is considered an attack on all. NATO was formed in response to the threat posed by the Soviet Union during the Cold War. Today, NATO consists of 31 member countries from North America and Europe. The organization promotes democratic values and enables members to consult and cooperate on defense and security-related issues. NATO also engages in crisis management and cooperative security efforts worldwide.