 Heinlein claimed to have written "Starship Troopers" in response to "calls for the unilateral ending of nuclear testing by the United States".Heinlein suggests in the book that the Bugs are a good example of Communism being something that humans cannot successfully adhere to, since humans are strongly defined individuals, whereas the Bugs, being a collective, can all contribute to the whole without consideration of individual desire.For Heinlein, personal liberation included sexual liberation, and free love was a major subject of his writing starting in 1939, with "For Us, the Living".