CAPITOL DOME EXPLODES?

That's more or less what happened. The Russian General who is governing the U.S. and who has somewhat fallen in love with the country and it's people comes up with the plan to stage the fake terrorist attack on Congress. The original plan was to nuke several cities (which I assume was also to be blamed on terrorists) but he calculated they could achieve the same emotional impact on the population with this much smaller (and essentially more humane) minor attack. The General is still so saddened by what he is forced to order that he commits suicide on the floor of one of the Congressional houses (forget which) - it's a pretty stark scene. All the bodies of the congressmen and women everywhere, the dome with a big hole blown out of it, pretty intense image.

This is designed as a kind of Reichstag Fire event, which Hitler used to solidify control in Germany by making the populace more pliable to accepting ever more extreme measures. Here it's used much the same way, a shocking event that so angers people they are willing to give away their history and their past and let the Russians break up the U.S. into smaller, more managable countries just so long as they can feel safe. Many would say that the public response after 9/11 has shades of this sort of thing, too, with people becoming more willing to accept extreme measures by the government than they otherwise wouldn't have allowed.