During the Vietnam War, World Airways shuttled thousands of military passengers through Oakland to their bases in Southeast Asia, and an international arrivals facility was built, allowing the airport to handle international flights for the first time. World Airways had broken ground on the World Airways Maintenance Center at Oakland International Airport. The maintenance hangar could store four Boeing 747s. It opened in May 1973. During its operation, World Airways contract maintenance services for 14 airlines in the facility. By 1988, World Airways vacated the Oakland maintenance base and moved its headquarters to Washington Dulles. That same year, United Airlines assumed the lease on the maintenance base.