The warning by Kim Yo Jong came after South Korea performed firing exercises in its tense land and sea borders with North Korea in the past two weeks.
The exercises were the first of their kind since South Korea suspended a 2018 agreement with the North aimed at easing frontline military tensions in June, Bussiness Standard reported.
"The question is why the enemy kicked off such war drills near the border, suicidal hysteria, for which they will have to sustain terrible disaster," Kim Yo Jong said in a statement carried by state media.
She said that South Korea's conservative government of deliberately escalating tensions as a way to escape a domestic political crisis. She said the riskiness of the South Korean drills is clear to everyone as they happened amid "a touch-and-go situation" established after the US, South Korea, and Japan recently held a new military exercise that North Korea views as a security threat.
In early June, South Korea fully suspended the 2018 inter-Korean military pact after North Korea flew balloons carrying manure, cigarette butts and waste paper across the border to protest South Korean activists scattering political leaflets in the North via their own balloons.
The military agreement -- reached during a short-lived era of reconciliation between the Koreas -- required the two countries to cease all hostile acts at border areas, such as live-firing drills, aerial surveillance and psychological warfare.
SD/PR