South Korea vows fast response to North; US deploys stealth jets

N Korea says the region is on brink of nuclear war in the wake of UN sanctions imposed for its February nuclear test

South Korea will strike back quickly if the North stages any attack on its territory, the new President in Seoul warned on Monday, as tensions ratcheted higher on the Korean peninsula amid shrill rhetoric from Pyongyang and the US deployment of radar-evading fighter planes.

North Korea says the region is on the brink of a nuclear war in the wake of United Nations sanctions imposed for its February nuclear test and a series of joint US and South Korean military drills that have included a rare US show of aerial power.

North Korea said on Saturday it was entering a "state of war" with South Korea in response to what it termed the "hostile" military drills being staged in the South. But there have been no signs of unusual activity in the North's military to suggest an imminent aggression, a South Korean defence ministry official said last week. (PYONGYANG'S MILITARY MIGHT)

"If there is any provocation against South Korea and its people, there should be a strong response in initial combat without any political considerations," President Park Geun-hye told the defence minister and senior officials at a meeting on Monday.

The South has changed its rules of engagement to allow local units to respond immediately to attacks, rather than waiting for permission from Seoul.

Stung by criticism that its response to the shelling of a South Korean island in 2010 was tardy and weak, Seoul has also threatened to target North Korean leader Kim Jong-un and to destroy statues of the ruling Kim dynasty in the event of any new attack, a plan that has outraged Pyongyang.