When North Korea launched a modernization of its broadcasting network in 2011, the Chinese company chosen to supply new TV and radio transmitters to the country faced a problem.

The location of broadcast towers in North Korea is so much of a state secret that engineers from the company weren’t permitted to travel to the DPRK to help install the transmitters, the company, Beijing BBEF Science and Technology, said on its website.

Instead, eight North Korean engineers spent a month in China being trained on how to install and operate the devices, which included a medium-power TV transmitter, several shortwave radio transmitters and a powerful More >