North Korea has offered to close its nuclear test site this month - and invited United States experts to verify the move.
Preparations for a Trump-Kim meeting have gained momentum since the Korean summit a week ago, which saw Pyongyang and Seoul promise to pursue the complete denuclearization of the peninsula and a permanent peace.
Earlier on Friday, Trump said that a time and a place had been set for the meeting with Kim, although he did not provide any details.
ReutersDonald Trump has previously threatened to "destroy" North Korea.
"China is ready to join with the global community, including North and South Korea, to play its due, active role in pushing forward the process for a political solution to the peninsula issue to finally achieve lasting peace in the region", Chinese state media cited Xi as saying.
The US government is looking into reports that three Americans arrested in recent years in North Korea had recently been relocated from a labour camp to a hotel near Pyongyang, as expectations grow that they will be released before the summit.
ICAO Asia and Pacific Regional Director Arun Mishra will travel to North Korea with the director of the agency's air navigation bureau, Stephen Creamer, to open discussion on air navigation and safety issues, according to Philbin.
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Earlier in the day, Bolton rebuked a New York Times article which reported that Trump was looking for options to scale back the number of USA troops in South Korea, calling it "utter nonsense". "If they are gone, we will lose proof that the Americans will defend us".
Moon moved quickly Friday to calm jitters about a USA troop reduction, especially among older conservatives who consider the US military's presence a sacrosanct symbol of national security and are deeply dubious of Kim's intentions.
President Donald Trump is touting his administration's tough approaches to North Korea and Iran. "But if a peace treaty is signed, the USA troops are bound to peter out".
North Korea readjusted its time zone to match South Korea's on Saturday and described the change as an early step toward making the longtime rivals "become one" following a landmark summit.
The DPRK adopted so-called Pyongyang time on the August 15 Liberation Day holiday in 2015, at the time arguing that conventional Korean Standard Time was based on the longitude of Japan and thus not suitable for Korea.
For decades, the USA military has protected South Korea and Japan under its nuclear umbrella, and it shares high-tech military surveillance and conducts annual joint war games preparing for any conflict.
"If they shake the alliance for the sake of denuclearizing North Korea", he added, "we will have an economic crisis before a security crisis".