The vast northern borders of the Soviet Union were wide open in many places during the early Cold War years, with little defensive radar coverage and limited detection capability. RB-50 aircraft of the 55th SRW flew many sorties along the periphery and, where necessary, into the interior. Initially, there was little opposition from the Soviet forces as radar coverage was limited and, if the overflying aircraft were detected, the World War II era Soviet fighters could not intercept the RB-50s at their high altitude.