in july 1972, air national guard units began supporting air force tanker task forces overseas with second-line kc-97 stratofreighter propeller-driven tankers and volunteer crews when needed. triggered by a 1974 decision by secretary of defense james r. schlesinger to save money, the ohio air national guard's 145th air refueling squadron acquired the ang's first jet tanker in april 1975 when it began converting from kc-97ls to kc-135a stratotankers. altogether, the air force transferred 128 older kc-135s to the air reserve components to retire the slow prop-driven tankers, which modern fighters had to reduce speed to nearly stall speed in order to refuel from.