A country, that no longer ago than 1 human lifetime, carried out the most sickening atrocities on its own species will have no issue at all in killing another supposedly intelligent species.
Hellfire Pass alone, just one of many rock cuttings on the Burma/Thai Railway, saw over 70 prisoners beaten to death for not working harder in the most atrocious conditions.
Unfortunately, in the story of human evolution, a number of races continue to hold dear and perpetuate brutish behaviours. ie. female genital mutilation, teeth filing, bull fighting, whaling etc.
