South Korean President Moon Jae-in said yesterday a thaw in relations between the two Koreas ahead of next month's Winter Olympics presented a "precious chance" for the United States and North Korea to discuss the North's weapons programmes.

North Korea is developing missile and nuclear technology amid regular threats to destroy the United States and Japan and in defiance of UN Security Council resolutions, prompting a war of words between the North and the United States.

But after a year of mounting tension, diplomacy focused on sport enabled the International Olympic Committee to announce on Saturday that reclusive North Korea will send 22 athletes to the February 9-25 Games.

The Olympics provided a "precious chance to open the door" for talks to resolve the nuclear issue and establish peace on the peninsula, Moon said at the presidential Blue House.

"But no one can be optimistic about how long the current mood for dialogue will last. We need wisdom and efforts to sustain the dialogue opportunities ... beyond the Olympics so that the inter-Korean talks will lead to talks between the United States and North Korea and other forms of dialogue".

South Korean police intervened when one group of protesters burned a picture of North Korean leader Kim Jong Un on the steps of Seoul's central train station where a delegation from the North had arrived.

Meanwhile, Tokyo held its first missile evacuation drill yesterday with volunteers taking cover in subway stations and other underground spaces that would double as shelters for the Japanese capital in the event of a North Korean missile strike.