North Korea's leader Kim Jong-un has said a nuclear launch button is "always on my table" and warned the US it will never be able to start a war.

North korea claims to have a fully deployable nuclear weapon, though there is still some international scepticism about its true capacity to carry out such an attack.

In his speech, Mr Kim re-emphasised his focus on the weapons programme, but implied the country still has a few stages left to go before achieving its ambitions. North Korea must "mass-produce nuclear warheads and ballistic missiles and speed up their deployment", he said.

He also said they would not use their weapons unless they felt that peace was threatened.

Mr Kim said he would also consider sending a delegation to the Games in Pyeongchang, South Korea, in February - a gesture which South Korea has previously suggested would be welcome.

"North Korea's participation in the Winter Games will be a good opportunity to show unity of the people and we wish the Games will be a success," he said.

"Officials from the two Koreas may urgently meet to discuss the possibility."

The president of the PyeongChang Games' organising committee, Lee Hee-beom, told South Korea's news agency Yonhap he was delighted to hear of the potential participation. The committee enthusiastically welcomes it. It's like a New Year's gift," he said.

The only two North Korean athletes who qualified for the Games are figure skaters Ryom Tae-Ok and Kim Ju-Sik.

Although the North has missed the official deadline to confirm their participation, the skaters could still compete with an invitation by the International Olympic Committee.

South Korea's President Moon Jae-in last month suggested delaying an annual joint military drill with US troops until after the Games. The North usually denounces any such exercises as a rehearsal for war.

When asked by reporters to respond to Mr Kim's latest threats, US President Donald Trump said, "We'll see, we'll see".

He was speaking at the sidelines of New Year's Eve celebrations at his Mar-a-Lago resort in Florida.