A quote on what to do with the Oregon militants:
https://en.wikiquote.org/wiki/James_Mattis
"I come in peace. I didnt bring artillery. But Im pleading with you, with tears in my eyes: If you fuck with me, Ill kill you all."
Send unarmed federal emissaries to the Malheur militants.
Talk to them directly.
Tell them how serious their situation is.
Tell them that they aren't above the law, just because they say so.
Tell them they can't reinvent the Constitution from centuries of judicial precedent just because they say so.
Saying it doesn't make it true.
Tell them how many years of jail-time await them if they ever get put before a legal court.
Tell them that it doesn't matter whether they recognize the legitimacy of said court.
Tell them that their legal theories are worthless and that they will not be able to talk themselves out from this situation.
Tell them that their time is up.
Tell them they have this many days to turn themselves in to law-enforcement for arrest.
If they turn themselves in, there's a chance the courts will show leniency.
"You have taken up arms against the government of the United States of America. Quit that bullshit. Now. If you don't, the United States of America will treat you like people who take up arms against the United States of America."