In our system, pretty much. As President Truman proved, and General Washington determined before him, the civilian leadership commands the military and not vice versa.

If the generals (admirals) disagree with civilian leadership such that they cannot in good conscience follow orders, then they can resign. No other choice is open to them.

This is exactly why Washington was able to convince his subordinates not to march on Philadelphia for the pay they were justly owed and why that over-inflated gasbag MacArthur resigned after challenging Mr. Truman.

As an aside, if you ever hear of a general undermining the civilian leadership, even if you agree with the general, side with the civilian lest you invite a solution worse than the problem.