The overlapping power transitions in East Asia’s three main economies promise to mark a defining moment in the region’s tense geopolitics. After the ascension in China of Xi Jinping, regarded by the People’s Liberation Army as its own man, Japan’s swing to the right in its parliamentary election seems set to fuel nationalist passion on both sides of the Sino-Japanese rivalry at a time when their brewing territorial spat in the East China Sea has created new risks to regional peace and stability.