United Kingdom: Background, Brexit, and Relations with the United States [March 12, 2018] [open pdf - 941KB]
"The modern relationship between the United States and the United Kingdom (UK) was forged during the Second World War. It was cemented during the Cold War, as both countries worked together bilaterally and within NATO to counter the threat of the Soviet Union. The United States and the UK are two of the five permanent members of the United Nations Security Council, and both are founding members of NATO. In the early 1990s, the UK was an important U.S. ally in the first Gulf War, and the two countries later worked together in stabilization and peacekeeping operations in the Balkans. The UK was the leading U.S. ally in the 2003 invasion of Iraq and subsequent stabilization operations, and it was the largest non-U.S. contributor to the NATO-led mission in Afghanistan. The UK remains an important U.S. partner in ongoing global security challenges, such as combatting international terrorism, countering the Islamic State terrorist group, and opposing Russia's annexation of Crimea and actions destabilizing Ukraine, including by supporting strong sanctions in response to these actions. The UK is also the sixth-largest economy in the world and a major financial center. The United States and the UK share an extensive and mutually beneficial trade and economic relationship, and each is the other's largest foreign investor."
CRS Report for Congress, RL33105