The statement “The parallel structure of these lines emphasizes that the pilot does not have much emotion for his enemies or his countrymen” best describes the effect of the parallelism in this excerpt.
W.B. Yeats in his poem “An Irish Airman Foresees His Death” speaks about an Irish soldier’s dilemma. The soldier being a patriot can neither take a back step on the battlefield nor he wants to harm his own people. He has no love for the people whom he has to protect but loves the people against whom he has to use his weapons. The parallel structure in the poem enhances the dilemma of the solider and makes it more specific to the readers. The repetition of the words in the lines or parallelism makes an idea or argument more specific and clear.