They will never tell you that you will be going against honest American Citizens. You will be told that you going against homegrown terrorists, or people suspected of being associated with extremists. And it will never be to uphold an unConstitutional law, or illegal order. It will be dressed to make you believe it will prevent the deaths of millions of Americans, or save the Republic. Extreme measure for an extreme, dire circumstance. Military personnel will be kept in the dark prior to any action, receive only skewed if not outright fabricated information, and deployed hastily in a "do or die" atmosphere.
"We must temporarily secure all civilian weapons in X area of operations to facilitate the work of CDC personnel in locating the stolen vials of weaponized airborne ebola that we believe to be in the hands of a widespread local network of homegrown terrorists with connections to Al Qaeda and Mexican drug cartels"
If you are military and have not made the premeditated, conscious decision that under no circumstances will you enter a citizen's home, and take anything from him regardless of legislation, or orders (something like Oathkeepers) then I am pretty sure our rulers will be able to get you to play a part in what ever devious plan they may have. Don't be a useful idiot.
Police forces (especially the larger ones) I am afraid will happily follow orders for home invasion and confiscation because that is what they are geared to do, and do so every single day. Thank you War on Drugs!