According to The Post, Sung Kim, a former United States ambassador in South Korea and former nuclear negotiator with North Korea, crossed the inter-Korean border to meet with Choe Son Hui, a senior diplomat in Pyongyang's Foreign Ministry.
In October 2000, then-leader Kim Jong Il, the current North Korean leader's father, sent Vice Marshal Jo Myong Rok to Washington on a then-unprecedented goodwill mission. Chol, the Vice Chairman of North Korea, heading now to NY.
CNN reported earlier Tuesday that Kim Yong Chol, the vice chairman of the Central Committee, was traveling to the USA for talks on North Korea - making him the most senior North Korean official to visit the United States since 2000.
The North Korean envoy was scheduled to fly to the United States on Wednesday after speaking to Chinese officials in Beijing, South Korea's Yonhap news agency said.
If the June 12 date stands, officials have only two weeks to finalize details such as where in Singapore the talks will take place and how internationally sanctioned North Korean officials will travel there.
The USA's ambassador to the Philippines is playing a key role in setting up the on-off-on meeting between North Korean leader Kim Jong-un and President Trump.
Sanders said that the US continues to actively prepare for President Donald Trump's expected summit with North Korean leader Kim Jong-un in Singapore. Randall Schriver, the assistant secretary of defense for East Asia and one of the officials who accompanied Secretary of State Mike Pompeo to Pyongyang earlier this month, also is in Seoul.
The United States and South Korea blacklisted Kim Yong Chol for supporting the North's nuclear and missile programs in 2010 and 2016, respectively.
The official traveling to NYC is General Kim Yong Chol, whom the Wall Street Journal reports is "often described as the North Korean leader's right-hand man".
But analysts say North Korea will be unwilling to cede its nuclear deterrent unless it is given security guarantees that the U.S. will not try to topple the regime.
Sung Kim will meet North Korean Foreign Ministry official Choi Sun Hee again on Wednesday on the border, Yonhap reported, citing a diplomatic source, adding that the agenda for the Trump-Kim summit would be roughly worked out.
If Trump is unable to negotiate those weapons away and unwilling to live in a world where North Korea poses a nuclear threat, then "you're going to have to do something to go after them at some point", the senator said. The countries were expected to hold another set of working-level meetings in Singapore to discuss protocol, security and other logistical issues for the summit.
The general is a notorious figure in South Korea, where he is accused of masterminding the 2010 sinking of the Cheonan navy corvette, which killed 46 sailors, an attack for which North Korea denies responsibility.
North Korea, in return, would demand the USA normalize its relations with it, ease sanctions against it and remove it from a list of state sponsors of terrorism, which could immediately help the North's economy.
It was a purge Kim Yong Chol would survive, cementing his reputation as a hawk in 2013 when he threatened to break the ceasefire that ended the Korean War and to turn the U.S. into a "sea of fire" with a nuclear strike. That was a shift from last week, when Trump announced in an open letter to Kim Jong Un that he had made a decision to "terminate" the summit following a provocative statement from the North. "This will be our last missile", Kim reportedly told Albright at the time, in an apparent reference to a medium-range ballistic missile the North fired over Japan two years earlier, which stunned the region.
He holds a number of senior positions within North Korea's communist hierarchy.
North Korea, which refers to its nuclear weapons program as its "treasured sword" keeping the country safe, has repeatedly said it is not interested in unilateral disarmament.