South Korean President Park Geun-Hye vowed "strong retaliation" Monday to any provocation by North Korea after Pyongyang declared it was formally at war with Seoul.
In a meeting with senior military officials and Defence Minister Kim Kwan-Jin, Park said she took the near-daily stream of bellicose threats emanating from the North "very seriously".
"I believe that we should make a strong and immediate retaliation without any other political considerations if (the North) stages any provocation against our people," she said.
Park, a conservative who had advocated cautious engagement with the North during her election campaign, has taken a more hardline position since assuming office in February, shortly after the North conducted its third nuclear test.
Military tensions between the two neighbours have been running high for weeks, with the North stepping up its hostile rhetoric against Seoul and Washington.
In protest at joint South Korean-US military drills, North Korea last month declared it was ripping up the armistice that ended the 1950-53 Korean War void and threatened a "pre-emptive nuclear strike" on South Korean and US targets.
On Saturday, it announced that it had formally entered into a "state of war" with South Korea.
Seoul and Washington have warned of severe repercussions in the event of any aggression, with the US deploying nuclear capable B-52 and B-2 stealth bombers, as well as F-22 stealth fighters over South Korea as a "deterrence".