SEOUL - In his upcoming summit with North Korean leader Kim Jong Un, US President Donald Trump is aiming to eliminate the country's arsenal of chemical and biological weapons as well as nuclear ones, the top American envoy to Japan said on Thursday (April 19).

"We had broad-ranging discussions on the topic and it extended beyond denuclearisation to the topics of chemical and biological weapons as well," US Ambassador to Japan Bill Hagerty said during a telephone conference with Asian reporters.

The conference came after Japanese Prime Minister Shinzo Abe wrapped up a two-day summit between Mr Trump at the Mar-a-Lago resort in Florida.

"President's intention is to see all of these weapons of mass destruction eliminated from the Korean Peninsula and the strategy remains the same in terms of complete, verifiable and irreversible aspects of denuclearisation," he said.

His remarks hint that removing chemical and biological weapons may also be under discussion in on-going preparations between Washington and Pyongyang for the Trump-Kim summit slated for May or early June, reported Yonhap news agency.

The US ambassador said that Trump will be more than happy to walk away from his planned summit with Kim if it does not produce any results.

"Let me be clear that a meeting between the two leaders are not an end in itself. President has no interest in having a meeting for the sake of meeting," Hagerty was quoted as saying by Yonhap.

"This is all aimed at making it certain that we have a meeting that is constructive and moving our agenda forward."

If the US has the sense that that's not the case, the president "is not going to waste his time," he said.

"Frankly, he's not interested in allowing more time to pass," he said.

He added that the US will ratchet up diplomatic sanctions and pressure on the North Korean regime in case the meeting does not lead to progress, reported Yonhap.