On November 2, Russia and Japan held their first-ever “two plus two” meeting, which brought together their respective foreign and defense ministers in Tokyo to discuss security cooperation. The meeting grabbed few headlines, but was far from routine: such gatherings are typically reserved for close allies, and for most of their modern history, Moscow and Tokyo have been anything but. Now, however, the two countries find themselves linked by a shared predicament in the Asia-Pacific. Both are secondary players in a region overshadowed by an increasingly assertive China, which has not hesitated to push against the boundaries of its neighbors....