North Korea welcomed foreign visitors and firms to a trade fair this week, showcasing home-grown products including the latest model of its sleek Jindallae smartphone. Diplomatically isolated and under biting sanctions over its nuclear and weapons programmes, North Korea has an ageing manufacturing base which analysts doubt has the ability to make high-quality consumer technology. Still, Pyongyang has touted Jindallae – “azalea” in Korean – as a convenient way for citizens to stay connected,...