A usurper is a loathsome creature; he and his enablers deserve nothing but ouster, disdain and prison or a firing squad.
I am an honorably discharged veteran:
To my brothers in service.
It is your duty to ignore and/or combat unlawful orders. Any order from a usurper is unlawful. Not only must you challenge his orders, to obey them is illegal and is a break from the oath you gave to the constitution and the republic.
Once again, your duty is not to one man or the office of the president it is to the constitution. If your word is worth anything you must not obey unlawful orders. Anything official form the current occupant of the White House is a criminal act and therefore unlawful.
Do not forsake this country or your oath for politics, comfort or peer pressure. The road will not be easy because the stakes are too high; nevertheless your duty is clear.
Thank you for your service, Semper Fi.