Courtesy Aussie bud Jono, we learn of this:
If successful, the plan would have seen humans and chimpanzees cross-breeding to create a new race of "living war machines", which ignored pain and fear and which thrived on hardship.
He suggests, and I have to agree, that the program may have been tried with more success in the west, although the hybrids are apparently now used as TV anchors and pundits.