If the Biden admin orders an illegal order, the ranks understand that THEY will go to go to jail, not the Biden admin people, and not many are willing to go to jail for Biden.
The military does not take an oath to Bitem or any other person, including Trump. The oath is to the Constitution.
This particularly applies to General Milley. Thence, to the Joint Chiefs. Thence to the generals under them.... and so on down to the Professional soldiers.