my assumption was he would use the military.
Once the Trump mass deportation process starts, they will use prison labor to supply slaves to farms and other understaffed industries. They will accomplish this through mass arrests of "others", such as left leaning people who have spoke out against Trump.
Their plan is to declare the insurrection act to stop protests and use the Presidential Emergency Action Documents to further their complete power grab, which will allow them to do things like:
authorized detention of “alien enemies” and other “dangerous persons” within the United States;
suspended the writ of habeas corpus by presidential order;
provided for various forms of martial law;
issued a general warrant permitting search and seizure of persons and property;
established military areas such as those created during World War II;
suspended production of the Federal Register;
declared a State of War; and
authorized censorship of news reports.
This will enable them to arrest left leaning people who have spoke out against trump. This is what they mean by the enemy within - the new "other" is the entire left. Trump has referred to this on video.