Why on Earth would NK want to threaten their big brother Russia?
Why on earth would Hitler invade his main supplier of oil? Why would Mao threaten invasion of Mongolia? Why would Li'l Kim threaten the United States? The point is perception. The Koreans have a long standing cultural animosity towards both Russia and China. Yes, at the present time, Russia and China are very useful to the DPRK, that doesn't mean that they actually like them. With the rhetoric against Russia's claim that the launch was an IRBM vice an ICBM, the Russians may be rethinking their relationship with the Norks. By the way, paranoia seems to be built into the Russian DNA.