President Donald Trump has undermined diplomatic efforts to solve the North Korea nuclear crisis, telling Secretary of State Rex Tillerson not to bother trying to negotiate with the rogue nation’s leader Kim Jong-un.

In a series of tweets Monday morning (AEST), Mr Trump said he “told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man”.

“Save your energy Rex, we’ll do what has to be done!” the President continued.

Mr Trump’s tweets come a day after Mr Tillerson said the US had direct lines of communication with North Korea and that he was trying to “calm things down” following months of escalating rhetoric over Pyongyang’s continued nuclear weapons and ballistic missile tests.

…Save your energy Rex, we'll do what has to be done!

— Donald J. Trump (@realDonaldTrump) October 1, 2017

Speaking from Beijing over the weekend, Mr Tillerson, said the US made it clear through its direct channels to North Korea that it was seeking peace through talks.

“We’ve made it clear that we hope to resolve this through talks,” he said.

“I think the most immediate action that we need is to calm things down. They’re a little overheated right now, and I think we need to calm them down first.”

When asked whether North Korea would come to the negotiating table, the secretary of state said: “We are probing, so stay tuned.”

Being nice to Rocket Man hasn't worked in 25 years, why would it work now? Clinton failed, Bush failed, and Obama failed. I won't fail.

— Donald J. Trump (@realDonaldTrump) October 1, 2017

The US is attempting to pressure North Korea to halt its weapons program, which has seen it launch repeated missile tests, as well as what it claims is a successful test ofa miniaturised hydrogen bomb which could be loaded on to a long-range missile.

China last week told North Korean businesses operating in its territory to close down as part of fresh United Nations sanctions against the reclusive state.

Former high ranking Pentagon official Dr Brad Roberts last week said Australia must develop greater missile defences to ward off a strike from North Korea.

“Unfortunately, Australia doesn’t really get to choose whether or not North Korea threatens it – it’s the choice that the North Korean leader [Kim Jong-un] makes,” he said.

Several North Korean missiles were recently spotted moved from a rocket facility in the capital Pyongyang, South Korea’s Korean Broadcasting System (KBS) reported on Friday.

The report cited an unnamed intelligence source saying South Korean and US officials detected missiles being transported away from North Korea’s Missile Research and Development Facility at Sanum-dong in the northern part of Pyongyang.

The report did not say when or where they had been moved.

– With agencies