Minds behind N Korea's secretive weapons

North Korea’s flurry of new missile tests, including what it calls “hypersonic” weapons, has underscored the importance of the country’s missile engineers and scientists, a group that is high profile within his government but opaque to outsiders.

Analysts said Kim Jong Un appears to be taking steps to institutionalise the missile forces, signalling his likely intent to make them a long-term, operational part of his military plans. Here's what we know – and what we don’t – about these key personnel...