North Korea's top leader Kim Jong Un has "guided" a large-scale striking exercise of long-range artillery targeting the South Korean presidential office, the official KCNA news agency reported on Friday.
Involved in the drill were more than 100 long-range artillery pieces of various calibres, including North Korea-style artillery, possessed by the large combined units on the front, the state media said.
In response to the threat, on the same day South Korea warned of stern and merciless retaliation if the North makes any provocations.
Seoul said that it has warned Pyongyang against threatening terrorist attacks on the head of state and the presidential office Cheong Wa Dae, which is also called Blue House, and has urged North Korea to immediately stop such "nasty and shallow-minded" acts.
On March 3, Kim "guided" the first test-firing of a new type large-calibre multiple rocket launcher.
On March 10, he watched a firing drill of ballistic rockets, which Seoul said were two short-range Scud missiles.
On March 21, Kim guided a second test-firing of a new, large-calibre multiple rocket launcher.
South Korea and the US kicked off their joint annual war games "Key Resolve" and "Foal Eagle" on March 7.
The "Key Resolve" command post exercise ended last week, but the "Foal Eagle" field training exercise would last until April 30.
Pyongyang has repeatedly condemned and called for a suspension of the joint military exercises, saying they are "war rehearsals for northward invasion".