"You cannot invade the mainland United States. There would be a rifle behind every blade of grass."
It seems like a no-brainer that an enemy force (Russia in this instance) would want to disarm the people they plan to attack/control.
The OP asked what I'd expect from a Russian Agent as President, and that's what I'd expect one of the first steps to be. I _wouldn't_ expect a russian agent who became president of the U.S. to fight for the 2nd Amendment/arming of citizens and to push for the EU to increase their military spending.
Sure, it could happen, but I wouldn't expect it.