NEW YORK - United States President Donald Trump and North Korean leader Kim Jong Un are set to meet in Vietnam on Feb 27 and 28, Mr Trump told Congress in his second State of the Union (SOTU) address on Tuesday (Feb 5).

He also suggested that a new missile control treaty could be negotiated with both Russia and China - and if not, the US would outspend both countries on missile development.

The site of the meeting with the North Korean leader was not mentioned, but is widely believed to be the seaside city of Da Nang.

"As part of a bold new diplomacy, we continue our historic push for peace on the Korean peninsula," Mr Trump said.

"Our hostages have come home, nuclear testing has stopped, and there has not been a missile launch in 15 months."

"If I had not been elected President of the United States, we would right now, in my opinion, be in a major war with North Korea with potentially millions of people killed.

"Much work remains to be done, but my relationship with Kim Jong Un is a good one. And Chairman Kim and I will meet again on February 27 and 28 in Vietnam."

The meeting will be closely watched in a region nervously following developments on the Korean peninsula.

While North Korea has refrained from testing missiles or nuclear devices since the two leaders met in a breakthrough summit in Singapore in June last year, and has returned the remains of many Americans killed in the Korean War, official talks on denuclearisation have not made any progress and official rhetoric on either side has been at odds.

US Director of National Intelligence Dan Coats echoed the convictions of many North Korea analysts in Washington when he told lawmakers last week that "North Korea will seek to retain its WMD (weapons of mass destruction) capabilities, and is unlikely to completely give up its nuclear weapons and production capabilities".

He added that US intelligence had observed "some activity that is inconsistent with full denuclearisation".

But he also acknowledged that North Korea had "halted its provocative behaviour".

Speaking at Stanford University on Jan 31, Special Representative for North Korea Stephen Biegun, who is due to visit Pyongyang on Wednesday, conceded that North Korea had not produced a declaration of its nuclear arsenal - a usual first step towards discussing practicalities of denuclearisation.

The US and North Korea had "no detailed definition or shared agreement on what denuclearisation entails", he acknowledged.

But Mr Biegun said Mr Trump was ready to declare an end to the Korean War - which was suspended in an Armistice which holds to this day. He added: "It's over. It's done. We are not going to invade North Korea."

"We are not seeking to topple the North Korean regime," he said.

What concessions, if any, America makes remains the biggest question. Mr Biegun said the US approach - essentially to break a deadlock - was becoming one of moving in tandem rather than "who's going to act first".

There is speculation over the consequences of formally ending the war, and what the details of a deal may be.

One possibility, say analysts, is that North Korea makes some token concessions on denuclearisation, but agrees to cut back its intercontinental ballistic missiles (ICBMs) - thus removing the threat to the territorial US of an ICBM-borne nuclear warhead.

And there is speculation that eventually, President Trump may move to bring some of the 28,500 US troops stationed in South Korea home.

However, in an interview over the weekend, Mr Trump said he was not going to bring troops home.

Mr Biegun, at Stanford, denied any contradiction between the US intelligence assessment of North Korea and the rosy statements about denuclearisation that have come from the White House.

"North Korea has given us little indication that they have yet made the decision to completely dismantle and destroy that capability. We all know that," he said.

"Negotiations were about trying to persuade Mr Kim to 'make a different set of choices'."

In broader terms in his State of the Union address, President Trump mentioned negotiations for a political settlement in Afghanistan, America's longest running war now in its 17th year.

"As a candidate for President, I pledged a new approach. Great nations do not fight endless wars," he said.

And in a swipe at critics, he said: "Under my Administration, we will never apologise for advancing America's interests."

"For example, decades ago, the United States entered into a treaty with Russia in which we agreed to limit and reduce our missile capabilities," he said, in a reference to the US withdrawal from the Cold War-era arms control agreement with Russia called the Intermediate-Range Nuclear Forces (INF) treaty.

Critics including arms control advocates, have said the US withdrawal will trigger a new missile race. Russia has already reacted by saying it will develop new missiles.

"While we followed the agreement to the letter, Russia repeatedly violated its terms," Mr Trump said.

He added: "Perhaps we can negotiate a different agreement, adding China and others, or perhaps we can't - in which case, we will outspend and out-innovate all others by far."