both the yc-14 and yc-15 met or exceeded the amst specifications under most conditions. however, the increasing importance of the strategic vs. tactical mission eventually led to the end of the amst program in december 1979. then, in november 1979, the c-x task force formed to develop the required strategic aircraft with tactical capability. the c-x program selected a proposal for an enlarged and upgraded yc-15 that was later developed into the c-17 globemaster iii. the lockheed c-130 hercules would be further improved into the c-130j and remains in service.