If today’s shooter had encountered less resistance and if he had been able to kill a significant number of Congressmen, it seems quite possible that martial law would be in effect (especially if he had then gotten away and there was any uncertainty as to who was acting).
So we are that close to an emergency situation.
If Trump were to take forceful action against globalists performing a soft coup in plain sight, then the lid would blow off. I think he would need to be sure that the armed forces were on his side in any such confrontation. This may be the real reason for the Russian interference fable — if there would be one thing to keep the armed forces within reach of the globalists in a coup situation, it would be an appeal to their anti-Soviet reflexes. This is what I suspect to be the real reason for what is otherwise a pretty obvious fairy tale about inflated or make believe interventions.
It is not possible to set marshal law on the entire USA. Do the math. In addition to a lack of personnel for such a folly it requires a Governor to agree to it. Not gonna happen.