Donald Trump promises North Korea will not develop a nuclear missile able to reach US territory

US President-elect Donald Trump took to Twitter again on Monday evening to promise North Korea would not develop a nuclear missile capable of reaching US territory.

His comment came a day after North Korean leader Kim Jong Un said his nuclear-capable country was close to test-launching an intercontinental ballistic missile (ICBM), raising the prospect of putting parts of the United States in range.

Trump dismissed the claim: "It won't happen".

North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the U.S. It won't happen!

— Donald J. Trump (@realDonaldTrump) January 2, 2017

Although Washington has repeatedly vowed that it would never accept North Korea as a nuclear state, Trump has not previously clearly stated his policy on the isolated Stalinist state.

South Korea's foreign ministry said Trump's comment, his first mention of the North Korean nuclear issue since the US election in November, could be interpreted as a "clear warning" to the North.

"Because of our active outreach, President-elect Trump and U.S. officials are clearly aware of the gravity and urgency of the North Korean nuclear threat," ministry spokesman Cho June-hyuck told a briefing.

"They are maintaining an unwavering stance on the need for sanctions on North Korea and for close cooperation between South Korea and the US".

Trump has not outlined a policy on North Korea but during the U.S. election campaign indicated he would be willing to talk its leader, Kim, given the opportunity.

The United States has for years dismissed North Korean calls for talks, insisting it must disarm first.

Instead, the United States and ally South Korea have responded to two North Korean nuclear tests and various missile tests last year with ever-more severe sanctions.