Comprised of England, Northern Ireland, Scotland, and Wales, the United Kingdom (UK) is a long-time friend and ally of the United States. As Brexit upends British politics, the traditional US-UK relationship remains more vital than ever to both countries and the larger transatlantic community. Despite wrestling with internal challenges, the UK plays an important leadership role in the international system as a permanent member of the United Nations Security Council, a NATO leader, and the bridge between Europe and the United States on issues of defense, security, sanctions, and trade.