When FLA begat FSTA and FTA, the choice was between A400M and C130J as FTA, although STSA was identified as a requirement until FTA became reality.
C310J provided tranche 1 of FTA and C130K was to be kept in service until tranche 2, A400M, became available; C-17 provided the STSA element. However, STSA appears to be established now as part of the FTA requirement as the C-17s are to be acquired conventionally.
It didn't help that Germany delayed A400M by not signing up on time, hence C130K must carry on for longer than was originally envisaged.
I think....??