US ambassador to the United Nations Nikki Haley says the UN Security Council has run out of options to deal with North Korea’s nuclear threats and may hand the matter over to the military.

Nikki Haley said the UN would happily turn the matter over to Defense Secretary Jim Mattis “because he has plenty of military options”.

“We have pretty much exhausted all the things that we can do at the Security Council at this point,” Ms Haley told CNN.

Mr Mattis said after North Korean leader Kim Jong-un tested a hydrogen bomb earlier this month that the US would answer any threat from the North with a “massive military response, a response both effective and overwhelming”.

US President Donald Trump has threatened to rain “fire and fury” on North Korea if it continued with its threats.

Ms Haley said that wasn’t an empty threat from the president but she declined to describe the president’s intentions.

“If North Korea keeps on with this reckless behaviour, if the United States has to defend itself or defend its allies in any way, North Korea will be destroyed and we all know that and none of us want that,” Ms Haley said.

Ambassador to the UN, Nikki Haley, says the Security Council is running out of options. Photo: Getty

“None of us want war. But we also have to look at the fact that you are dealing with someone who is being reckless, irresponsible and is continuing to give threats not only to the United States, but to all their allies, so something is going to have to be done.”

The warnings came a day after Kim pledged to continue its weapons programs, saying North Korea is nearing its goal of “equilibrium” in military force with the US.

The UN Security Council has voted unanimously twice in recent weeks to tighten economic sanctions on North Korea.

Mr Trump, in a tweet, asserted that long lines for fuel were forming in North Korea, saying that was “too bad”.

The President also mocked Kim as “Rocket Man” in a tweet, saying he and South Korean President Moon Jae-in discussed the country during their latest telephone conversation on Saturday.

Asked about Mr Trump’s description of Mr Kim, national security adviser H.R. McMaster said “Rocket Man” was “a new one and I think maybe for the President”.

I spoke with President Moon of South Korea last night. Asked him how Rocket Man is doing. Long gas lines forming in North Korea. Too bad!

— Donald J. Trump (@realDonaldTrump) September 17, 2017

But, he said, “That’s where the rockets are coming from. Rockets, though, we ought to probably not laugh too much about because they do represent a great threat to all.”

General McMcaster said Kim is “going to have to give up his nuclear weapons because the president has said he’s not going to tolerate this regime threatening the United States and our citizens with a nuclear weapon”.

Asked if that meant Mr Trump would launch a military strike, General McMaster said: “He’s been very clear about that, that all options are on the table.”

Kim has threatened Guam, a US territory in the Pacific, and has fired missiles over Japan, a US ally. North Korea also recently tested its most powerful bomb.

North Korea will be high on the agenda for world leaders this coming week at the annual meeting of the UN General Assembly.

Mr Trump wrote on Twitter that he asked the South Korean President how “Rocket Man” was doing. Photo: Getty