Reykjavík Keflavík Airport, is the largest airport in Iceland and the country’s main hub for international transportation. In 2013 it handled 3,2 million passengers. The main carrier at Keflavík is Icelandair. The airport is almost exclusively an international airport; most domestic flights are flown from Reykjavik Airport.
The airport was built by the US militaryduring World War II. During the war the airport complex only served military purposes, but at war’s end it became a refueling stop for the quickly developing international civil aviation crossing the Atlantic. At the withdrawal of U.S. forces in 1947, the airport was handed over to Iceland and renamed Keflavík Airport.
Source: Wikipedia