North rea's propaganda machine branded the US President a "lunatic" and "human reject" in response to comments Donald Trump made during his tour of Asia.

The Rodong Sinmun, the mouthpiece of the ruling Workers' Party, claimed Mr Trump's statements were an "open declaration of war" against North Korea.

The newspaper took apart one of the speeches the president delivered in South Korea in which Mr Trump taunted Kim Jong-un.

North Korea's propaganda machine said: "The worst crime for which he can never be pardoned is that he dared to malignantly hurt the dignity of the supreme leadership of the DPRK."

But Mr Trump ignored Pyongyang's latest swathe of insults and announced the United States would re-design the rogue nation as a 'sponsor of terror', triggering "very large" sanction on the already heavily-disciplined state.

US Secretary of State Rex Tillerson said the decision was taken to close "a few loopholes" in the US strategy towards North Korea.

Speaking at the White House, Mr Tillerson said: "I think it is very symbolic on the one hand because it just points out again what a rogue regime this is. How brutal this regime is and how little they care about the value of human life.

"I think in that in of itself makes a strong statement on the nature of this regime. As I’ve said the practical effects may be limited but we’re hopefully closing off a few loopholes with this."

He remarked Mr Trump's tour of Asia helped the United States strengthen its relationship with allies in the region and helped to gather support against the Kim regime.

Mr Tillerson said: "This is all part of this strategy of continuing to turn the pressure up. And we continue to turn the pressure up on North Korea by getting other countries to join and take action on their own.

"During our visit to Vietnam, they have committed that they are going to curtail activities further with North Korea. Malaysia has indicated their curtailment. Singapore has cut off all trade with North Korea. The Philippines have cut off all trade.

"This is taking effect all around the world and we think, as it takes effect, this continues to tighten the pressure on the Kim regime with an intention to have him understand this is only going to get worse."