North Korea ruled out talks and threatened to increase its nuclear arsenal in a fresh warning to Donald Trump's administration as the US President set off on a tour of Asia.

Trump departed for his first presidential trip to Asia Friday, with tensions over North Korea's nuclear and missile threats looming large. He is due to arrive in South Korea Tuesday, after first visiting Japan.

The North's state-run KCNA news agency said in a commentary that the US should be disabused of the "absurd idea" that Pyongyang would succumb to international sanctions and give up its nuclear weapons, adding that it is in "the final stage for completing nuclear deterrence".

"It had better stop daydreaming of denuclearisation talks with us", said the commentary titled "Stop dreaming a daydream".


"Our self-defensive nuclear treasure sword will be sharpened evermore unless the US hostile policy toward the DPRK is abolished once and for all", it said, using an acronym for the official name of North Korea.

The White House said Trump will deliver a speech at South Korea's National Assembly and urge "common resolve in the face of shared threat".

But there is widespread concern in South Korea that the US president's visit might worsen the situation if Trump fails to rein in his fierce rhetoric.

US President Donald Trump and North Korean leader Kim Jong Un during a news program at the Seoul Train Station. Photo / AP
US President Donald Trump and North Korean leader Kim Jong Un during a news program at the Seoul Train Station. Photo / AP

Trump and the North's leader Kim Jong-un have traded insults and threats of war in recent months.

"Because of his tendency to veer off the script, many Koreans are worried that he may let loose", Professor Yang Moo-Jin of the University of North Korean Studies told AFP.

Some 500 protesters took to the streets in Seoul Saturday, chanting slogans and waving banners as they accused Trump of bringing the Korean peninsula to the brink of war.

"No Trump, No War", read one of the banners, while others portrayed the US President wearing a Nazi uniform.

Nearby, a rival group of some 100 Trump supporters, including many military veterans, chanted: "Welcome to Korea, We believe in Trump".


Trump, who dismissed direct talks with Pyongyang as "waste of time", will meet with President Moon Jae-In, who came to power early this year advocating for engagement with Pyongyang, a stance denounced as "appeasement" by Trump.

Professor Koh Yu-Hwan at Dongguk University, a leading policy adviser to the government, said Seoul expected Trump to avoid putting Moon in a quandary by renewing pugnacious threats against the North, particularly with South Korea hosting the Winter Olympics in February next year.

Moon has had to dial back his policy of engagement with the North in the face of Pyongyang's persistent nuclear and missile tests.

A president's dilemma

Trump is being pulled in different directions as he heads to Asia on a gruelling 12-day trip.

The president's loyal supporters are eager to hear him take a hard line on the Chinese trade and economic practices he railed against as a candidate. But many in his administration are pushing Trump to sweep those concerns aside as he works to pressure China's Xi Jinping to tighten the screws on North Korea.

The first half of Trump's trip is expected to be dominated by North Korea. While trade issues will most certainly be a recurring theme, the administration has signalled that it does not expect to announce any significant concessions from China on trade or market access - areas in which Trump hammered China throughout his campaign, accusing the country of "ripping us off."


Back then, Trump was vowing to slap a 45 per cent tariff on Chinese goods and suggesting that Japan and South Korea obtain nuclear weapons to protect themselves instead of relying on the U.S.

Kim Jong Un at an undisclosed location in North Korea. Photo / AP
Kim Jong Un at an undisclosed location in North Korea. Photo / AP

"We can't continue to allow China to rape our country, and that's what they're doing," Trump told an Indiana rally crowd last year. Trump's former chief strategist, Steve Bannon, has described the U.S. as "at economic war with China" and described Chinese efforts to pressure North Korea to abandon its nuclear program as a "sideshow."

Asked by Fox News' Laura Ingraham on the eve of his trip whether he would push Xi in areas such as intellectual property theft, government subsidies and the dumping of products, Trump demurred.

"You have to understand something very important: We have a problem called North Korea," Trump said.

Instead, Trump is expected to announce several major Chinese purchase deals from U.S. companies - potentially on planes, agricultural products and natural gas exports that could be worth billions.

It's "a way of distracting from the fact that there's been no progress in China on structural reform, market access, or the big issues that the president has tried to make progress on with regard to China," said Elizabeth Economy, director for Asia Studies at the Council on Foreign Relations.