The Special Relationship is a term that is often used to describe the political, social, diplomatic, cultural, economic, legal, environmental, religious, military and historic relations between the United Kingdom and the United States or its political leaders. The term first came into popular usage after it was used in a 1946 speech by former British prime minister Winston Churchill. Both nations have been close allies during many conflicts in the 20th and the 21st centuries, including World War I, World War II, the Cold War, and the war on terror.
Although both governments also have close relationships with many other nations, the level of cooperation between the UK and the US in trade and commerce, military planning, execution of military operations, nuclear weapons technology, and intelligence sharing has been described as "unparalleled" among major world powers. The close relationships between British and American heads of government, including that between Margaret Thatcher and Ronald Reagan and later between Tony Blair and both Bill Clinton and George W. Bush have been cited as examples of the special relationship. At the diplomatic level, characteristics include recurring public representations of the relationship as "special", frequent and high-profile political visits and extensive information exchange at the diplomatic working level.