No, no, no, that's not what I even implied. If one believes the law is relatively immaterial to what "government" does, especially in extreme cases such as the subject here, then using the UN while the main bulk of our troops are out of the US is a given.
So tell me then,
How many countries in the world have a coherent heavy lift capacity to import enough troops to enforce this martial law?
Last time I did a quick check of worldwide military capabilities there was just one, with 2 others looking to build such a heavy lift capability.
Like to gues what these countries are? The only country with a coherent heavy lift is the US. The other countries are China and Russia.
So how will all that heavy lift arrive unchallenged? Because it will be our own heavy lift that is doing it. In other words our military.
Of course that last statement is an oxymoron. If martial law ever happens it will not be Blue Helmets unless they are blue helmets on US troops. (Sorry, that's another oxymoron).
It doesn't take much to sink an invasion fleet that sails without the support of massive naval superiority and air superiority. Since we have both right now a few warships and a handful of aircraft could sink the invasion fleet mid-stride. Our troops not stopping the invasion is little different to them crushing the populace under their boots.
Our dominance of the sky and sea will not change for at least another 20 or so years. What heavy lift China and Russia have by then remains to be seen but I fully expect that the US will be the leader for the next 50 years or so, although during that time the the edge we hold will be eroded. I like to think that in the event of a large scale government sell-out the military will actually do what it is tasked to do first and foremost- defend the constitution.
So if martial law happens before then it will be our troops opressing our citizens.
If you want to set the scenario in 2045 I might think differently.