Does koko really understand sign language

Her caregiver, Francine "Penny" Patterson, reports that Koko is able to understand more than 1,000 signs of what Patterson calls "Gorilla Sign Language" (GSL).[2] In contrast to other experiments attempting to teach sign language to non-human primates, Patterson simultaneously exposed Koko to spoken English from an early age. Reports state that Koko understands approximately 2,000 words of spoken English. 

Because the vietnam war was fought in an especially brutal and untraditional way