Let say that a country like Iran or Nk start using BTC to finance some of their activities or organization like "alqaida" ask ransom in BTC.
The US government killed way more people than Al Qaida and Iran and many people use USD...
FYI:

yeah man, i got really pissed about the whole cambodia thing. the khmer rouge were just misunderstood is all
plus, al qaeda has this. it doesnt drop bombs, but it does kick ass
