Throughout the Cold War, the nation of Iceland was a member of the North Atlantic Treaty Organisation (NATO) and allied with the United States, hosting a US military presence in Keflavík Air Base from 1951 to 2006.
In 1986, Iceland hosted a summit in Reykjavík between United States President Ronald Reagan and Soviet Premier Mikhail Gorbachev, during which they took significant steps toward nuclear disarmament.
Five years later, in 1991, Iceland became the first country to recognize the renewed independence of Estonia, Latvia, and Lithuania when they broke away from the Soviet Union.
Early in World War II, the neutral Kingdom of Iceland had declined an offer of British protection. A month after the occupation of Denmark by Nazi Germany in 1940, the British invaded Iceland, violating the country's neutrality, over the formal protest of Iceland's regent, Sveinn Björnsson. In 1941, the British arranged for the United States to take over occupation of the country so that British troops could be used in other arenas of the war. After pressure from the British, the Icelandic government eventually agreed to US occupation, and on June 7, 1941 five thousand US troops arrived in Iceland. The United States supported the founding of the Republic of Iceland in 1944 and promised to withdraw its troops once the war ended, but failed to do so when Nazi Germany was defeated in 1945. As World War II was winding down, the United States tried to persuade Icelandic statesmen to agree to permanent American military basing in Iceland. The pro-Western Icelandic Prime Minister Ólafur Thors considered such an agreement impossible at the time due to public opposition. When the Americans made a formal basing request in October 1945, Ólafur Thors rejected it.