Meanwhile, leader of South Korea and the U.S. talked on the phone for nearly an hour Tuesday night, Korea time.
During it, they agreed to look into holding a one-on-one meeting on the sidelines of the UN General Assembly later this month.
Our Blue House correspondent Hwang Hojun reports.

Should President Moon attend the UN General Assembly in New York later this month,... the Presidents of South Korea and the U.S. could meet on the sidelines to hash out future strategies on issues regarding the Korean Peninsula.
Presidents Moon Jae-in and Donald Trump had a fifty-minute phone call on Tuesday night, just a day before the South Korean envoys headed to Pyongyang to discuss the inter-Korean summit that will be held in Pyongyang this month.
According to the Blue House press release, President Moon briefed his U.S. counterpart on the reason for sending envoys to North Korea to discuss preparations for the third summit between him and North Korean leader Kim Jong-un.
Moon also emphasized the need for a fresh round of inter-Korean dialogue to reduce tensions between the two Koreas, which will ultimately contribute to denuclearization and the establishment of permanent peace on the Korean Peninsula.
However, after the phone conversation, the Blue House was cautious to confirm that President Moon will, in fact, attend the General Assembly; while White House spokesperson Sarah Sanders said the two leaders agreed to meet later this month. The Blue House said in a separate readout that the two leaders agreed to quote "explore the idea of meeting in person" on the sidelines of the General Assembly in New York.
The phone conversation between the two Presidents came less than 2 weeks after President Trump canceled U.S. Secretary of State Mike Pompeo's planned visit to Pyongyang, citing lack of progress on the denuclearization of the Korean Peninsula.
Hwang Hojun, Arirang News.