In 1965, the Vietnam War expanded over the 17th parallel into North Vietnam's panhandle and the Red River Delta. Despite its lead in hardware - with access to advanced radars, beyond visual range and close-in heat seeking ordnance, along with large numbers of heavy-bombers and fighter aircraft - the United States failed to achieve air superiority over North Vietnam. The People's Army of Vietnam, supported by its Communist allies, wielded a mixture of sophisticated air-to-air and surface-to-air weapons to devastating effect. By the summer of 1965, American fighters were being lost at a rate of an entire squadron every 45 days. By the end of that year, the U.S. Air Force had lost a total of 174 aircraft and 16 pilots, with another 35 aircrew members missing.