He said: “At the end of the day, the big thing that North Korea is worried about is China.
“China can end the North Korean regime anywhere from about six to nine months by turning off the oil supplies that go into the country.
“That’s what the sword of Damocles hanging over Kim Jong-un’s head ultimately is.
“And, of course, what China is petrified of is a collapsed regime and tens of millions of impoverished North Koreans flooding into their country and bringing with them all of the humanitarian crisis that would issue.
“So, China has a real interest in keeping the border erected and keeping the regime in place.
“All of the global diplomatic efforts for years and years now, have all been focussed around this very thing.
“About getting China to lie the law down to North Korea and say no, nukes are too far.”
The trip, which began on Sunday and ended on Wednesday, was Kim’s first known journey abroad since he assumed power in 2011 and analysts believe it may have been used to serve as preparation for upcoming summits with South Korea and the US.
Beijing has traditionally been North Korea’s closest ally but ties have been frayed by Kim’s pursuit of nuclear weapons and China’s backing of tough UN sanctions in response.
According to Xinhua, Kim told Xi the situation in the region was improving because North Korea has taken the initiative to ease tensions and put forward proposals for peace talks.
Kim said: ”It is our consistent stand to be committed to denuclearisation on the peninsula, in accordance with the will of late President Kim Il Sung and late General Secretary Kim Jong Il.”
He said North Korea was willing to talk with the US and hold a summit between the two countries.
Kim added: “The issue of denuclearisation of the Korean Peninsula can be resolved if South Korea and the US respond to our efforts with goodwill, create an atmosphere of peace and stability while taking progressive and synchronous measures for the realisation of peace.”
Xi told Kim in return that both sides had stated repeatedly that their traditional friendship should be passed on and developed better.
He said: ”This is a strategic choice and the only right choice both sides have made based on history and reality, the international and regional structure and the general situation of China-North Korea ties.
“This should not and will not change because of any single event at a particular time.”
Washington, which has been briefed on the visit by Beijing, said its hardline “maximum pressure” policy was starting to pay off.
White House Press Secretary Sarah Huckabee Sanders said: “The Chinese government contacted the White House earlier on Tuesday to brief us on Kim Jong-un’s visit to Beijing.
“The briefing included a personal message from President Xi to President Trump, which has been conveyed to President Trump.
“The United States remains in close contact with our allies South Korea and Japan.
“We see this development as further evidence that our campaign of maximum pressure is creating the appropriate atmosphere for dialogue with North Korea.”
But President Donald Trump refused to ease pressure on North Korea after he was briefed about the meeting between the two leaders.
The American President tweeted: ”Received message last night from XI JINPING of China that his meeting with KIM JONG UN went very well and that KIM looks forward to his meeting with me.
“In the meantime, and unfortunately, maximum sanctions and pressure must be maintained at all cost!”