If someone wants to walk on a train with explosives they can and even if they start screening people there are going to be extra long lines and guess where the suicide bomber is going to be?
The DHS offers nothing but fear and false hope, after our nation was attacked why the hell are they continuing to do this?

If there are people planning on attacking us, go out there an arrest them,. You don't need the patriot laws, color coded systems, DHS, etc they don't work and they offer nothing but fear and false hope. During clinton years the FBI went right into pakistan and arrested the CIA shooter all without causing a scene.