China’s fourth aircraft carrier, widely believed to be the country’s first with a nuclear-powered system, could launch as early as next year, according to US researchers, as Beijing pursues a fleet capable of projecting naval and air power far beyond its shores. A launch in 2027 would coincide with the centenary of the People’s Liberation Army, with the anniversary falling on August 1. Beijing has previously used major military anniversaries to showcase developments in its armed forces. The...