Independent experts say the North could have enough fissile material for anywhere between about a dozen and 60 nuclear bombs.
When asked about Kim Jong Un's denuclearisation plans, Trump said, "Kim Jong Un is very serious about the denuclearisation and has already destroyed a missile testing facility and have agreed to destroy another one".
However, Harris, the former commander of US forces in the Pacific, endorsed Trump's plan to pause major military exercises with the South, saying the U.S.is in a "dramatically different place" from where it was a year ago.
In their joint statement Kim agreed to the "complete denuclearisation of the Korean Peninsula" - a stock phrase favoured by Pyongyang that stopped short of longstanding U.S. demands for North Korea to give up its atomic arsenal in a "verifiable" and "irreversible" way.
Putin noted that the standoff over North Korea "worried the entire world and could entail grave consequences, including a major military conflict".
The documentary is nearly explicitly through Kim's perspective as it follows his journey to Singapore-Trump doesn't appear until halfway through the documentary. In exchange, the United States pledged to make unspecified "security guarantees" and stop joint military exercises with South Korea. In a clip shared by the BBC, Trump is shown meeting various North Korean officials, including a North Korean military general.
Mr Trump's surprise promise to call off military exercises, describing them as expensive and "provocative", delighted North Korea and China but caught key United States allies off-guard.
Otto Warmbier's parents hope historic summit leads to 'something positive'
Before they signed the document, Trump and Kim had been involved in one-on-one talks, which came after months of planning. The United States and DPRK will join their efforts to build a lasting and stable peace regime on the Korean Peninsula.
In an interview recorded in Singapore but broadcast on the US television channel, Fox News, late on Wednesday in the US, Trump said that a withdrawal of US troops from South Korea had not been discussed at the summit. "But we have made very clear, that the sanctions and the economic relief that North Korea will receive will only happen after the full denuclearization, the complete denuclearization of North Korea". On Thursday, North Korean state media broadcasted a 42-minute documentary from the summit, including footage of Trump attempting to shake the officer's hand but saluting him instead.
Trump also said he hopes the thaw in relations with North Korea will eventually allow him to withdraw USA troops from the peninsula.
In North Korea, the official KCNA news agency described the summit as an "epoch-making meeting" that would help foster "a radical switchover in the most hostile (North Korea)-US relations".
Even as experts weighed the implications of Trump's Singapore summit with Kim, the U.S. president struck a typically bullish note in a series of announcements.
BISHOP: You know, they did a lot more than they've really I think ever done to pressure North Korea.
Overall the South Korean foreign minister voiced strong support for the Trump-Kim declaration agreement, calling it a "historic turning point" toward peace that will bolster political momentum toward action.
Trump's remarks followed a historic summit in Singapore between the President and his North Korean counterpart.