The District of Columbia should be on lockdown, no one allowed in or out, until the inauguration. The National Guard should be stationed at all points of ingress and egress. The Guard should establish an inner perimeter encircling the Capitol building.

Better yet: Congress should disperse, not to a secret safe house, that won't remain secret long, they should go back to their districts. Conduct business, including impeachment, via Zoom or other virtual medium. The inauguration should not go forward in the Capitol. Biden can be sworn in anywhere. LBJ was on the plane as it flew back from Dallas. No target is better than a "soft" or even hard target.