North Koreans in shock as cash is 'banned'

All other enterprises and services based on cash, including markets, long-distance bus services, barbers, saunas and bath houses, have been suspended until the revaluation is completed next week.

Don't be overly shocked, the US and other Western nations have been slowly moving to this also.'
The difference is it is being done slowly, not overnight.

There was confusion after the announcement of the measure, which requires North Koreans to swap existing won notes with new ones at an exchange rate of one to 100, knocking two zeroes off their value. There is a cap of 100,000 won (£419) per family, which means that anyone with significant holdings of cash will have their savings wiped out

I would think this would hurt the ruling elite more than the average N.K. citizen.
Times online

I've always thought that if a Stalinist regime were to contribute anything useful to the world it could be to experiment with a no-money society. I'm amazed no Marxist regime has done away with currency - "To each according to his needs, from each according to his abilities" - Lenin.

Unfortunately, this is probably about some other agenda.