Of the 200,000, (plus 100,000 maybe Guard and Reserve) shooters how many would you need just to control NYC with a population of nearly 9 million? You have around 37,000 cops in NYC. Factor in private security and other state police agencies, probably around 50,000 available enforcers. Just a guess. So you currently have 50,000 plus enforcers trying to protect a population or property in a City of nearly 9 million. To lock down that city under martial law it would take half or more of the military shooters just for NYC. I am shooting from the hip here, but there is not enough military available to protect DC and one major city.
You would be surprised to learn how few of the experienced warfighters from the war on terror are actually still on active duty. Some very senior enlisted and officers, but most were broken or tired. The left or retired. You have a large force of untested GenZ and Millennial's. NYC would eat them alive.