Michael Hirsh for Politico Magazine:

According to nearly a dozen retired officers and current military lawyers, as well as scholars who teach at West Point and Annapolis, an intense if quiet debate is underway inside the U.S. military community about what orders it would be obliged to obey if President-elect Donald Trump decides to follow through on his previous warnings that he might deploy troops against what he deems domestic threats, including political enemies, dissenters and immigrants.

On Nov. 18, two weeks after the election, Trump confirmed he plans to declare a national emergency and use the military for the mass deportations of illegal immigrants.

One fear is that domestic deployment of active-duty troops could lead to bloodshed given that the regular military is mainly trained to shoot at and kill foreign enemies. The only way to prevent that is establishing clear “rules of engagement” for domestic deployments that outline how much force troops can use — especially considering constitutional restraints protecting U.S. citizens and residents — against what kinds of people in what kinds of situations. And establishing those new rules would require a lot more training, in the view of many in the military community….