What is the importance of Vietnam in the novel, Tomcat in Love?

Thomas serves one year fighting in the Vietnam war. Here he witnesses the blatant and violent destruction of a beautiful mountainside. He takes a Vietnamese lover, which helps distract himself from the horrors of war. This is also where he becomes so disillusioned with the state of humanity that he calls an airstrike on his own men. He awards himself the Silver Star for valor and realizes that nothing really matters, surrounded by death and devastating destruction. When he returns from Vietnam, he often thrashes about in his sleep, as he is haunted from the memories he has there.