On April 4, 1949, the US and 11 other nations (Belgium, Great Britain, France, Luxembourg, Italy, Iceland, Canada, the Netherlands, Denmark, Norway, and Portugal) formed the North Atlantic Treaty Organization (NATO), which still exists today.
The treaty organization was a defensive military alliance against the threat of the Soviet Union, which meant that each member country promised to defend other member countries if they were ever attacked by an external threat. In 1955, West Germany was admitted to NATO. Allowing West Germany to again have a military alarmed the Soviet Union as NATO now presented a unified defensive perimeter against Soviet interests.
In response to the threat of NATO, on May 14, 1955, the Soviet Union and its European satellite states signed the Warsaw Pact, which is short for the Warsaw Treaty of Friendship, Cooperation, and Mutual Assistance.
The European satellite states involved in the pact were Albania, Poland, Romania, Hungary, East Germany, Czechoslovakia, and Bulgaria. They were called satellite nations because these countries were under the influence and pressure of the Soviet Union.
On October 24, 1945, the United Nations (UN) was established to be an intergovernmental organization aimed at maintaining international peace and avoiding the atrocities that people had experienced with World War II. Currently, there are 193 members in the UN. In addition to peace-keeping efforts, the UN also performs humanitarian and environmental endeavors, such as vaccinating children, dealing with climate change, and providing food to people in need.