There are other options than American or Russian (is that what you mean by ils/an120? What types do you really mean?)..
South Africa ordered A400M, but cancelled it, supposedly due to the price having escalated - but the price given as the reason for cancellation was greatly exaggerated. A new order would be politically difficult, but would meet the requirement.
The KC-390 is another option, & it'd provide opportunities for local industry (as A400M did, & neither C-130J nor C-17 do).
C-17 is probably too expensive.