Some Japanese conservatives do not like it when Hokkaido is called a historically non-Japanese Ainu land. Russia has recognized the Ainu as an indigenous people of the Russian nation, so Hokkaido could be claimed as "Russian."
Quote
Jeffrey J. Hall 
@mrjeffu
Replying to @mrjeffu
The author claims that Putin's 2018 recognition of the Ainu as an indigenous people of Russia can be used to justify an invasion to "protect" the Ainu from Japanese discrimination. This would be similar to Putin's invasion of Ukraine to protect "Russians."sankei.com/article/202311