As Japan marks Northern Territories Day, Moscow appears to be trying to boost patriotism among residents on the Russian-controlled islands claimed by Tokyo.

A Japan-Russia treaty signed on February 7, 1855 recognized that the four islands belong to Tokyo. Japan calls the islands the Northern Territories.

Russia controls the islands. Japan claims them. The Japanese government maintains the islands are an inherent part of Japan's territory. It says the islands were illegally occupied after World War Two.

Russian media reported that groups of cars with the letter "Z" written on them ran through the streets of the islands. The letter is a symbol of support for the country's invasion of Ukraine. Reports also said that islanders sent supplies to Russian soldiers in Ukraine.

Russian media also said a funeral was held for a soldier from Etorofu, one of the four islands, who died in Bakhmut in Ukraine's Donetsk region.

A soldier from Shikotan, another of the four islands, was reportedly praised as a hero in special classes at schools on the island after he died in Ukraine.

In March, Russia announced a suspension of negotiations on a peace treaty with Japan, including talks on the issue of the four islands. This came after Japan, along with Western nations, imposed sanctions on Russia over the invasion.