North Korean leader Kim Jong Un on Sunday guided a combat drill by a special operation battalion, state media reported.
Photos published in North Korean newspaper Rodong Sinmun appeared to show a mockup of South Korea's presidential Blue House as a target.
"Well done, the enemy troops will have no space to hide themselves, far from taking any counteraction," Kim reportedly said after watching the drill, according to North Korean state media KCNA.
The report specifically mentioned the South as a target for North Korean forces, as Kim offered advice on a "guerilla warfare" invasion of the country's southern neighbor and rival.
"(Kim) said that if the service personnel of the unit are to conduct bold combat actions with the southern part of Korea as their theater, they should stage intensive drills for marching, firing, swimming, overcoming natural obstacles and acquiring ability to maneuver in fields under the simulated conditions of an actual battle," the report added.
South Korean officials were quick to condemn the movements.
"(We) view the drill from yesterday as a childish act to display that their system is undiminished, in response to our internal situation," South Korean Unification Ministry spokesman Jeong Joon-hee said.
"Kim Jong Un has been continuously visiting its military units since November and it has been escalating tension. We strongly condemn it."
The North has defied the international community in recent months, through repeated missile launches and nuclear tests
. In response, the UN Security Council imposed what Secretary-General Ban Ki-moon called the "toughest and most comprehensive sanctions"
The South Korean government remains on alert for any attempt by the North to take advantage of the political turmoil enveloping Seoul.
President Park Guen-hye was impeached
on Friday after weeks of mass protests over accusations her closest confidante had unauthorized access to the highest levels of government.
Park will remain in the Blue House for the duration of a constitutional court deliberation on her impeachment, but will be stripped of all duties and powers while the process plays out.
In a phone call last week with Defense Minister Han Min-koo, acting President Hwang Kyo-ahn said that North Korea possibly could use the political upheaval to stir up trouble south of the 38th parallel and that the South Korean military should maintain its readiness.
"While retaining a watertight national defense posture, the government will work closely with the international community to thoroughly respond to the North Korean nuclear problem," Hwang said.
Last week, before the impeachment vote, Seoul accused its insular northern neighbor of hacking its military intranet
and leaking confidential information.