The decision to send anti-ship missiles to a number of disputed Kuril islands in the Pacific has reportedly angered Japanese officials.
Tokyo has now pledged to respond with appropriate force to what it sees as Russian aggression.
According to insiders, the Japanese are looking to end a 70-year-old dispute over the islands, using weapons if necessary.
It comes as the Japanese government said yesterday it would be carrying out a massive evacuation drill for its population to prepare for the risk of nuclear attack.
The drill will reportedly be held in March next year and is in response to threats from nuclear-capable countries, such as North Korea.
Tubby tyrant Kim Jong-un has flexed his nuke muscles at Japan in the past, threatening to send devastating missiles their way.