Ben: a 51% attack has always been an acknowledged way to cheat the system; and the computing power of NSA (and others like Russian Federation, China) make not just a 51% attack, but worse possible. Remember — NSA can readily take down the server farms that do much of the Bitcoin processing, leaving NSA nodes in control. Not likely, but as the article argues — in a war or just short of war with North Korea it is very possible that NSA would be charged to take the system down temporarily, or long term. Just a short term minor attack disruption may be enough to kill off the “digital gold” allure of bitcoin and lead to a huge and permanent drop in value. This wouldn’t hurt the U.S. government, but could be big loss for North Korea.