Kim Shin-jo, who later reinvented himself as a Christian pastor, took part in the failed 1968 attempt to assassinate Park Chung-hee.
President Kim Jong Un gave his full support to Moscow at a meeting with a top Russian official in Pyongyang, North Korean state media said on Saturday.
The warning came after Kim accused the US of escalating tensions on the Korean Peninsula through its alliance with South Korea and Japan.
At a meeting of the Workers’ Party of Korea (WPK) this week, North Korean leader Kim Jong-un criticised dozens of officials for drunken misconduct.
Kim visited the nuclear material production base and the Nuclear Weapons Institute, according to state media.