It is about a number of the Kuril Islands (Iturup, Kunashir, Shikotan and Habomai) and (rarely) on the southern part of Sakhalin.
First Vice President of the Academy of Geopolitical Problems, Konstantin Sivkov sees main reason for this policy in that "the Japanese are convinced Russia is weakening, and its armed forces have come to such a state when they can not provide full security."