Claiming the U.S. government was complicit in 9-11 isn't a "typical leftist" point of view. And if you want to equate leftist with "anti American," you are really off the rails. It may be, as is claimed, that the intelligence and law enforcement officials in the "W" admin didn't connect the dots, or just failed to take the warnings seriously, and there were a number of warnings. At worst, that can be construed as incompetence rather than a deliberate act of betrayal.
As to the second amendment, I think part of the problem here is that most people have never read the full amendment, and not just the single phrase the gun lobby has seized. More to the point, I have no problem with people buying guns, if there are no legal issues or mental health issues, although I think there ought to be some training so people don't accidentally shoet the wrong person, or a person when they are aiming for a target or they're deer hunting. We require training for cars, because they can cause immense damage to the driver, passengers, or other people and their property if not handled properly. Why not with a gun?
I won't get into the assault weapons argument, since I am not one to use guns. But more thorough background checks, and a centralized database may help prevent some of this gun violence. I also don't see why gun violence in the U.S. is so much worse than other developed nations. Doesn't that raise a red flag? Doesn't that demonstrate something has to change?