Unless you're an administration apparatchik or a student being served daily doses of Kool-Aid in the liberal lunchroom, your Top-5 list of internal threats to the USA -- to homeland security, as it were -- would probably include most or all of the following potentialities...
- Terrorism
- Violence and chaos resultant of a manmade disaster.
- Violence and chaos resultant of a natural disaster.
- Lawlessness that is unmanageable by local and state police.
- Espionage