After World War 2 many countries believed in the principle of collective security which means what?

After World War II, the principle of collective security emerged as a belief that nations should work together to prevent aggression and maintain peace. This concept asserts that an attack against one member of a collective security arrangement is considered an attack against all, prompting a united response. It underpinned the formation of organizations like the United Nations, aimed at promoting cooperation and deterring conflict through diplomatic means and, if necessary, collective military action.