Kim's hostile remark during his inspection of a military unit came just two days after the North blew up part of inter-Korean roads and railways across the border earlier this week.
The detonation means "not only the physical closure but also the end of the evil relationship with Seoul which persistently lasted century after century and the complete removal of the useless awareness about fellow countrymen and unreasonable idea of reunification," Pyongyang's state-run Korean Central News Agency quoted its leader as saying.
Tensions between the two Koreas have been escalating as North Korea has resorted to threats against South Korea, including accusing the South of infiltrating drones to drop propaganda leaflets over Pyongyang and threatening to attack if they are detected again.
Pyongyang has also recently amended its constitution to define Seoul as a "hostile state."
