The Pentagon stopped working with Marvel Studios on "The Avengers" movie over concerns that the film doesn't realistically portray military bureaucracy, particularly in its depiction of the S.H.I.E.L.D. organization, officials say. "To whom did S.H.I.E.L.D. answer? Did we work for S.H.I.E.L.D.? We hit that roadblock and decided we couldn't do anything," said Phil Strub, the Defense Department’s Hollywood liaison.