Which figure of speech is used in this text?
Let both sides explore what problems unite us instead of belaboring those problems which divide us. Let both sides, for the first time, formulate serious and precise proposals for the inspection and control of arms . . . Let both sides seek to invoke the wonders of science instead of its terrors.
—President John F. Kennedy, inaugural address

 - anaphora
 - chiasmus
The text uses anaphora, the repetition of the same word or words at the beginning of several phrases or clauses.
Kennedy repeats the words let both sides at the beginning of each sentence.