The Senkaku islands and the risk of war with China
A set of remote, uninhabited islands which lie between Japan and China are a constant source of tension. Japan insists they are part of its sovereign territory. China also claims ownership and sends militarised coastguard ships to patrol the region.
If China were to land its forces on the islands, Japan might open fire with fighter planes.
America also has a big stake in the game. Earlier this year, the U.S. Defense Secretary Lloyd Austin affirmed that the U.S. military would respond to any attack on the Senkakus.
In this podcast for Japan Story, Duncan Bartlett explains to Andrew Peaple why feelings on the issue are running so high.