North Korean leader Kim Jong-un crossed the border into Beijing on his signature green train early on Tuesday to attend China’s celebration of the formal surrender of Japan in World War II, relying on a slow but specialised form of transport that the reclusive country’s leaders have used for decades. Compared with North Korea’s ageing fleet of passenger aircraft, the bulletproof trains offer a safer and more comfortable space for a large entourage, security guards, food and amenities, and a...