Naval Air Station Keflavik (NASKEF) is a United States Navy station at Keflavík International Airport, Iceland, located on the Reykjanes peninsula on the south-west portion of the island. NASKEF was closed on 8 September 2006, and its facilities were taken over by the Icelandic Defence Agency as their primary base until 1 January 2011, when the Agency was abolished and the base handed over to the Icelandic Coast Guard, which has since then operated the base. US forces would return to Keflavik starting from 2016. The base was built during World War II by the United States Army as part of its mission to maintain the defense of Iceland and secure northern Atlantic air routes. It served to ferry personnel, equipment, and supplies to Europe. Intended as a temporary wartime base under an agreement with Iceland and the British, U.S. forces withdrew by 1947 but returned in 1951 as the Iceland Defense Force resident on a North Atlantic Treaty Organization (NATO) base. The base was regularly visited by the American military and other NATO allies for military exercises, NATO Air Policing, and other tasks. In 2017, the United States announced its intention to modify the largest hangar on the Icelandic base in order to house the new Boeing P-8 Poseidon ASW aircraft being introduced. History Background After being granted self-governance by Denmark in 1918 with the signing of the 25-year Danish-Icelandic Act of Union, Iceland followed a policy of strict neutrality in international affairs. In 1939, with war imminent in Europe, the German Reich pressed for landing rights for Deutsche Luft Hansa's aircraft for alleged trans-Atlantic flights. The Icelandic government turned them down. A British request to establish bases in Iceland for the protection of the vital North Atlantic supply lines after German forces occupied Denmark and Norway in April 1940 was also turned down in accordance with the neutrality policy. In response, on 10 May 1940 the people of Reykjavík awoke to the sight of a British invasion force. The government of Iceland protested the invasion but asked the populace to treat the occupying force as guests. Following talks between British Prime Minister Winston Churchill and President Franklin D. Roosevelt of the United States, Iceland agreed to a tripartite treaty under which United States Marines were to relieve the British garrison in Iceland on the condition that all military forces be withdrawn from Iceland immediately upon the conclusion of