After World War II, the United States and Western Europe saw the importance of working together. They took important steps to create lasting cooperation. One of these steps was the Marshall Plan. Under this plan, the United States agreed to provide financial aid to European countries to help them rebuild their cities and infrastructures after World War II. European countries also cooperated together economically, by forming organizations like the European Economic Community. Another step taken for cooperation was the creation of the North Atlantic Trade Organization (NATO). NATO was a military agreement in which all members agreed to defend each other if one of the nations was attacked. The United Nations (UN) was the third step to creating lasting peace. The UN is an organization that tries to prevent conflicts that may lead to war between nations.