WASHINGTON - It is imperative that South Korea and the United States manage the crisis with North Korea to prevent further escalation or any kind of military clash which could quickly spiral out of control, South Korea's Foreign Minister Kang Kyung Wha told an audience at the Centre for Strategic and International Studies (CSIS).

"It is very likely that North Korea will conduct further provocations and under these circumstances it is imperative that we - Korea and the United States together - manage the situation with astuteness and steadfastness," she said.

"There cannot be another war in the region; there cannot be another outbreak of war on the Korean peninsula," she said. "The consequences would be devastating not just for the Korean peninsula but for north east Asia and indeed for the whole international community."

Stressing repeatedly that South Korea and the US did not seek the collapse of North Korea, she said however "North Korea must take heed of our messages and change course and the first step would be for the North to stop its provocations."

"The political and diplomatic effort toward the denuclearisation of North Korea and improvements of South and North Korean relations can and must be pursued," she emphasised. "The call for diplomacy is the clear wish of the public both in Korea and the United States as recent polls indicate," she added.

"Sanctions and diplomacy are diplomatic tools, not meant to bring down or collapse North Korea, but to bring it to the negotiating table for serious denuclearisation talks."

But sanctions and diplomacy must also be accompanied by strong deterrent capabilities, the minister added.

She was speaking at the CSIS forum in Washington just hours after her North Korean counterpart told journalists in New York "since the United States declared war on our country, we will have every right to make countermeasures, including the right to shoot down United States strategic bombers even when they are not inside the airspace border of our country".

"The whole world should clearly remember it was the US who first declared war on our country," Foreign Minister Ri Yong Ho told reporters.

White House Press Secretary Sarah Sanders dismissed the notion of the US having declared war as "absurd" however, telling journalists in Washington "Our goal is still the same : peaceful denuclearisation of North Korea through maximum diplomatic and economic measures."