I'd heard of Kuril islands dispute. The "northern territories" are apparently the four of the Kuril islands that Japan claims as their own but Russia occupies.

I'd heard of Kuril islands dispute. The "northern territories" are apparently the four of the Kuril islands that Japan claims as their own but Russia occupies. https://en.wikipedia.org/wiki/Kuril_Islands_dispute https://en.wikipedia.org/wiki/Kuril_Islands_dispute