"Military Colonist" is a term that has gone out of fashion in this brave new world of "No Human Being is Illegal" and "Every Refugee Deserves to be Resettled."
The university history professor with an office full of fake Indian jewelery and a view of the parking lot will lecture on the military colonies of the Roman period, always careful to emphasize their eventual fate. And he may even get up to the 16th century. But he'll stay away from the present.
But if you are going to take land or seize power, you will need military colonists to hold it. The military colonist may be an ex-soldier, but he's more likely to be someone the empire, present or future, doesn't particularly need or have a use for. The Czars used serfs. The present day military colonist who shows up at JFK or LAX may also be a peasant with even less value to his culture.
Mexico's military colonists are not military. Often they aren't even Mexican. But they have managed to take back California without firing a shot. Unless you count the occasional drive by shooting.
While the United States sent tens of thousands of soldiers to try and hold Iraq and Afghanistan only to fail; Mexico took California with a small army of underpaid handymen who claim entire cities and send back some 20 billion dollars a year. As conquests go, it's not hard to see who did more with less.