About:

• This is the first time in about two decades that Japan has used this phrase to describe the dispute over the Kuril Islands.
  
  
• Japan had been using softer language since 2003, saying that the dispute over the islands was the greatest concern in Russia-Japan bilateral ties.
  
  

What are the Kuril Islands/ Northern Territories?

• These are a set of four islands situated between the Sea of Okhotsk and the Pacific Ocean near the north of Japan's northernmost prefecture, Hokkaido.
  
  
• Both Moscow and Tokyo claim sovereignty over them though the islands have been under Russian control since the end of World War II.
  
  
• The Soviet Union had seized the islands at the end of World War II and by 1949 had expelled its Japanese residents. Tokyo claims that the disputed islands have been part of Japan since the early 19th century.
  
  

What lies behind the dispute?

• According to Tokyo, Japan’s sovereignty over the islands is confirmed by several treaties like the Shimoda Treaty of 1855, the 1875 Treaty for the exchange of Sakhalin for the Kuril Islands (Treaty of St. Petersburg), and the Portsmouth Treaty of 1905 signed after the Russo-Japanese war of 1904-05 which Japan had won.
  
  
• Russia, on the other hand, claims the Yalta Agreement (1945) and the Potsdam Declaration (1945) as proof of its sovereignty and argues that the San Francisco Treaty of 1951 is legal evidence that Japan had acknowledged Russian sovereignty over the islands.