"The authorities have found ingenious ways to turn those new technologies against the North Korean people who are adopting them."

Warnings are appearing on Instagram accounts in North Korea that claim access to the popular photo-sharing app is being denied and the site blacklisted for harmful content.

Despite widespread poverty, malnutrition and decades of crippling U.S.-led economic sanctions, Pyongyang has poured resources into training thousands of hackers who regularly target bitter rival Seoul.