>> his successor, mark esper, would not weigh-in on mattis saying the internal divisiveness posed the greatest threat to american democracy. chairman dunford a month from retirement, went a step further. >> i will not now, nor will i take off the uniform make judgments about the president of the united states. i won't do it. >> mattis and general dunford served in concert together as u.s. marines. shep? >> shepard: we reported the concern about a new north korean sub. what are you learning about that? >> in his first press conference as secretary, mark esper was asked about north korea's new weapons and recent missile tests. >> we're concerned about their short range ballistic missile tests. we want to understand what they're doing and why they're doing it. on the other hand, we won't