North Korea blasted the South Korean defense minister on Sunday for "reckless" remarks about Seoul's ability to strike Pyongyang, warning of retaliation after conducting a record number of weapons tests this year.
South Korean defense minister Suh Wook had said Friday that his army had missiles with "the ability to accurately and quickly hit any target in North Korea".
The comments drew condemnation from Kim Yo Jong, the sister of North Korean leader Kim Jong Un and a key policy adviser.
"His reckless and intemperate rhetoric about the 'preemptive strike' has further worsened the inter-Korean relations and the military tension on the Korean Peninsula," she said according to official North Korean news agency KCNA.
"South Korea may face a serious threat owing to the reckless remarks made by its Defense Minister... South Korea should discipline itself if it wants to stave off disaster," Kim added.
In a separate statement on Sunday, Pak Jong Chon, secretary of North Korea's ruling party central committee, also warned the South off any military action against Pyongyang.
"Our army will mercilessly direct all its military force into destroying major targets in Seoul," he said. Pak did not specify which targets.
North Korea has resumed its sanctions-breaking weapons tests with an unprecedented blitz this year, last month firing its first intercontinental ballistic missile at full range since 2017.
Long-range and nuclear tests were paused when Kim and then US president Donald Trump engaged in a high-profile bout of diplomacy that subsequently collapsed in 2019. Talks have since stalled.
North Korea will this month mark the 110th anniversary of the birth of founder Kim Il Sung -- the grandfather of current leader Kim, who likes to mark key domestic anniversaries with military parades or launches.
Tensions between both sides are also set to ramp up as South Korea's president-elect Yoon Suk-yeol takes office next month.
During Yoon's campaign period, he had threatened a pre-emptive strike on the North "if necessary", and vowed to "teach some manners" to Kim.