The military doesn't want to get involved

What military leaders understand—and those advocating for our military to use its popularity to wade into politics do not—is that once the military consents to become a political actor, the public will consider it one. At that point, its standing will drop to that of elected officials, journalists, and the Supreme Court. A 2012 study by Golby, Kyle Dropp, and Peter Feaver for the Center for a New American Security found that political endorsements by retired military figures don’t particularly increase public support for the cause or politician in question, but they do diminish the respect the public has for the military as an institution.

Military leaders’ concern isn’t for their own approval ratings; it is for the effect that such a drop in stature will have on recruiting, on cohesion in the ranks among service members of different political views, and on the relationship between military experts and the elected officials whom they advise while serving on policy councils.

That hasn’t stopped political partisans from trying to draft off the military’s popularity. One video at the Democratic convention showed a retired marine in military uniform endorsing Joe Biden at a veterans’ event. Convention organizers unquestionably knew that the clip violated military norms, because it included a disclaimer that the appearance of individuals in uniform didn’t constitute a Defense Department endorsement of Biden.