In other news, Blue House Deputy National Security Adviser Kim Hyun-chong is reportedly in Washington to discuss the issue of individual tours to North Korea.
Citing diplomatic sources, a local daily said that Kim met with a string of White House officials to discuss sanctions and inter-Korean cooperation projects.
It added that defense cost-sharing and ways to resume North Korea-U.S. talks were also on the table.
This comes after reports that Choi Jong-kun secretary to the president for peace planning had also visited the U.S. to discuss related matters.
South Korea has been looking to get inter-Korean relations back on track amid the nuclear standoff between Pyeongyang and Washington.
President Moon Jae-in had also said that individual tours do not violate UN sanctions and that they could help bring North Korea back to the negotiating table.