The diplomatic foreign relations of the United Kingdom are conducted by the Foreign, Commonwealth and Development Office, headed by the foreign secretary. The prime minister and numerous other agencies set policy, and many institutions and businesses have a voice and a role to play.
The United Kingdom was the world's foremost power during the 19th and early 20th centuries, most notably during the so-called "Pax Britannica"a period of unrivaled supremacy and unprecedented international peace during the mid-to-late 1800s. The country continued to be widely considered a superpower until the Suez crisis of 1956, and the dismantling of the British Empire gradually diminished the UK's dominant role in global affairs. Nevertheless, the United Kingdom remains a great power and a permanent member of the United Nations Security Council. The UK is a founding member of AUKUS, the Commonwealth, the Council of Europe, the European Court of Human Rights, the G7, the G20, the International Criminal Court, NATO, the OECD, the OSCE, the World Health Organization, and the World Trade Organization, additionally the UK is a member of CPTPP. The UK was also a founding member state of the European Union, however due to the outcome of a 2016 membership referendum, proceedings to withdraw from the EU began in 2017 and concluded when the UK formally left the EU on 31 January 2020, and the transition period on 31 December 2020 with an EU trade agreement. Since the vote and the conclusion of trade talks with the EU, policymakers have begun pursuing new free trade agreements with other global partners.
In March 2026, the UK government announced that it would make deep cuts to its foreign aid budget, including a 56% reduction in bilateral aid to African countries, as funds are redirected toward defence spending.
History
Following the formation of the Kingdom of Great Britain (which united England and Scotland) in 1707, British foreign relations largely continued those of the Kingdom of England. British foreign policy initially focused on achieving a balance of power in Europe, with no single country dominating the continent's affairs. This policy remained a major justification for Britain's wars against Napoleon, and for British involvement in the First and Second World Wars. Secondly, Britain continued to expand its colonial "First British Empire" through migration and investment.
France was the chief enemy until Napoleon's defeat in 1815. It had a much larger population and a more powerful army, but a weaker navy. The British were generally successful in their many wars. The notable exception, the American War of Independence (1775–1783), saw Britain, without any major allies, defeated by the American colonials who had the support of France, the Netherlands, and (indirectly) Spain. A favoured British diplomatic strategy involved subsidising the armies of continental allies (such as Prussia), thereby turning London's enormous financial power to military advantage. Britain relied heavily on its Royal Navy for security, seeking to keep it the most powerful fleet afloat, eventually with a full complement of bases worldwide. British dominance of the seas was vital to the formation and maintenance of the British Empire, achieved by maintaining a navy larger than the next two largest navies combined before 1920. The British generally stood alone until the early 20th century, when they became friendly with the US and made alliances with Japan, France, Russia, and Germany, their former antagonist, now an ally.
1814–1914
The 100 years were generally peaceful—a sort of Pax Britannica enforced by the Royal Navy. There were two important wars, both limited in scope. The Crimean War (1853–1856) saw Russia's defeat and ended its threat to the Ottoman Empire. The Second Boer War (1899–1902) saw the defeat of the two Boer republics in South Africa, and the Boxer Rebellion happened the same year. London became the world's financial centre, and commercial enterprise expanded across the globe. The "Second British Empire" was built with a base in Asia (especially India) and Africa.
First World War
1920s
After 1918, Britain was a "troubled giant" that was less of a dominant diplomatic force in the 1920s than before. It often had to give way to the United States, which frequently exercised its financial superiority.F.S. Northedge, The troubled giant: Britain among the great powers, 1916–1939 (1966). The main themes of British foreign policy included a leading role at the Paris Peace Conference of 1919–1920, where Lloyd George worked hard to moderate French demands for revenge on Germany.Erik Goldstein, Winning the peace: British diplomatic strategy, peace planning, and the Paris Peace Conference, 1916–1920 (1991). He was partly successful, but Britain soon had to moderate French policy toward Germany further, as in the Locarno Treaties of 1925.Frank Magee, "‘Limited Liability’? Britain and the Treaty of Locarno." Twentieth Century British History 6.1 (1995): 1–22.Andrew Barros, "Disarmament as a weapon: Anglo-French relations and the problems of enforcing German disarmament, 1919–28." Journal of Strategic Studies 29#2 (2006): 301–321. Furthermore, Britain obtained "mandates" that allowed it and its dominions to govern most of the former German and Ottoman colonies.Wm Roger Louis, "The United Kingdom and the beginning of the mandates system, 1919–1922." International Organization 23.1 (1969): 73–96.
Britain became an active member of the new League of Nations, but its list of major achievements was slight.Peter J. Yearwood, Guarantee of Peace: The League of Nations in British Policy 1914–1925 (2009).Susan Pedersen, "Back to the League of Nations." American Historical Review 112.4 (2007): 1091–1117. in JSTOR
Disarmament was high on the agenda, and Britain played a major role, following the United States, at the Washington Naval Conference of 1921 in working toward naval disarmament among the major powers. By 1933, disarmament agreements had collapsed, and the issue became rearming for a war against Germany.Raymond G. O'Connor, "The 'Yardstick' and Naval Disarmament in the 1920s." Mississippi Valley Historical Review 45.3 (1958): 441-463. in JSTOR
Britain was partially successful in negotiating better terms with the United States regarding the large war loans which Britain was obliged to repay.Frank C. Costigliola, "Anglo-American financial rivalry in the 1920s." Journal of Economic History 37.4 (1977): 911-934. Britain supported the international solution to German reparations through the Dawes Plan and the Young Plan. After the Dawes Plan had helped stabilize Germany's currency and lowered its annual payments, Germany was able to pay its annual reparations using money borrowed from New York banks, and Britain used the money received to pay Washington.Patrick O. Cohrs, The unfinished peace after World War I: America, Britain and the stabilization of Europe, 1919-1932 (Cambridge, 2006). The Great Depression starting in 1929 put enormous pressure on the British economy. Britain revived Imperial Preference, which meant low tariffs within the British Empire and higher barriers to trade with outside countries. The flow of money from New York dried up, and the system of reparations and debt payments died in 1931.
In British domestic politics, the emerging Labour Party had a distinctive and suspicious foreign policy rooted in pacifism. Its leaders believed that peace was impossible because of capitalism, secret diplomacy, and the arms trade. Labour stressed material factors, ignoring the psychological memories of the Great War and the highly emotional tensions surrounding nationalism and national boundaries. Nevertheless, party leader Ramsay MacDonald devoted much of his attention to European policies.Henry R. Winkler. "The Emergence of a Labor Foreign Policy in Great Britain, 1918-1929." Journal of Modern History 28.3 (1956): 247-258. in JSTOR
1930s
Vivid memories of the horrors and deaths of the First World War inclined many Britons—and their leaders in all parties—to pacifism in the interwar era. This led directly to the appeasement of dictators (notably Mussolini and Hitler) to avoid their threats of war.Patrick Finney, "The romance of decline: The historiography of appeasement and British national identity." Electronic Journal of International History 1 (2000). online
The challenge came from those dictators, first from Benito Mussolini, Duce of Italy, then from Adolf Hitler, Führer of a much more powerful Nazi Germany. The League of Nations proved disappointing to its supporters; it failed to resolve any of the threats posed by the dictators. British policy involved "appeasing" them in the hope that they would be satisfied. By 1938, it was clear that war was looming and that Germany had the world's most powerful military. The final act of appeasement came when Britain and France sacrificed Czechoslovakia to Hitler's demands at the Munich Agreement of September 1938.David Faber, Munich, 1938: Appeasement and World War II (2010) Instead of satiation, Hitler menaced Poland, and at last Prime Minister Neville Chamberlain dropped appeasement and stood firm in promising to defend Poland (31 March 1939). Hitler, however, cut a deal with Joseph Stalin to divide Eastern Europe (23 August 1939); when Germany did invade Poland in September 1939, Britain and France declared war, and the British Commonwealth followed London's lead.Donald Cameron Watt, How War Came: Immediate Origins of the Second World War, 1938–39 (1990)
Second World War
Having signed the Anglo-Polish military alliance in August 1939, Britain and France declared war against Germany in September 1939 in response to Germany's invasion of Poland. This declaration included the Crown colonies and India, which were directly controlled by Britain. The dominions were independent in foreign policy, though all quickly entered the war against Germany. After the French defeat in June 1940, Britain and its empire stood alone in combat against Germany until June 1941. The United States provided diplomatic, financial, and material support, starting in 1940, especially through Lend Lease, which began in 1941 and reached full strength in 1943. In August 1941, Churchill and Roosevelt met and agreed on the Atlantic Charter, which proclaimed "the rights of all peoples to choose the form of government under which they live" should be respected. This wording was ambiguous and would be interpreted differently by the British, Americans, and nationalist movements.Keith Sainsbury, Churchill and Roosevelt at War: the war they fought and the peace they hoped to make (New York University Press, 1994).
Starting in December 1941, Japan overran British possessions in Asia, including Hong Kong, Malaya, and especially the key base at Singapore. Japan then marched into Burma, headed toward India. Churchill's reaction to the United States' entry into the war was that Britain was now assured of victory, and the future of the empire was safe. Still, the rapid defeats irreversibly harmed Britain's standing and prestige as an imperial power. The realisation that Britain could not defend them pushed Australia and New Zealand into permanent close ties with the United States.
Postwar
Economically in dire straits in 1945 (saddled with debt and dealing with widespread destruction of its infrastructure), Britain systematically reduced its overseas commitments. It pursued an alternate role as an active participant in the Cold War against communism, especially as a founding member of NATO in 1949.F.S. Northedge, Descent From Power British Foreign Policy 1945-1973 (1974) online