Members of the U.S. military have the legal right to refuse orders they believe are unlawful, but they risk violating military laws of obedience if the order is in fact lawful, experts in military law say.

Senator Mark Kelly faces a Pentagon review after appearing in a video urging troops to reject illegal orders while using his retired Navy rank. The Department of Defense says he is the only participant still subject to the UCMJ and cited laws that protect military discipline.