Troop strength for the DC area is projected to be 10,000 within a week, and 15,000 by the time of the inauguration. They will be armed and authorized to use force. Remember that military use of force rules are much more broad than those used by civilians (including police). I would point out that this puts the number of US troops in DC to roughly the level of troops in Baghdad in 2003, when Bush visited the troops in Baghdad for Thanksgiving.
The FBI is afraid that local and state police are sympathetic to the right. What this means, I don't know, but coupled with the alert that all 50 state capitols are in danger from armed conservative insurrectionists, makes me wonder if we aren't going to see a massive call out of domestic troops in the near future.