why did the vietnam war seem morally wrong to o'brien the narrator? S

Even at age twenty-one, Tim knows the difference between a moral action and a socially acceptable action. He knows that being willing to die so that he will not be embarrassed does not make him brave. He wishes he could be truly brave and stand up for what he believes in--he truly does believe that Vietnam is wrong--but something holds him back. He knows it is fear and shame. He does not want to be called a coward, so he goes to war. Even years later, he sees this as pathetic.