Whose melody is interpolated in the opening of Metallica's “Don't Tread on Me”?

The opening of Metallica's “Don't Tread on Me” interpolates a melody by Leonard Bernstein.

The melody comes from “America,” a song Bernstein composed for the musical West Side Story. Metallica incorporated the recognizable figure into the beginning of the Black Album track, creating a brief connection between a heavy-metal recording and one of the best-known works of twentieth-century American musical theater.

The credit is sometimes misidentified as belonging to Stephen Sondheim, who wrote the lyrics for West Side Story. Bernstein composed the music, while Sondheim wrote the words, so Bernstein is the answer when the question asks whose melody is used.

“Don't Tread on Me” takes its title and imagery from the Gadsden flag, whose coiled snake also appears on the album cover. The song was issued to rock radio after the album's release but was not released as a commercial single. Its opening musical reference is therefore a deeper album detail rather than a fact tied to one of the five official singles.