US National Security Advisor Mike Flynn on Sunday held a phone conversation with his South Korean counterpart Kim Kwan-jin, expressing hope over the development of the Seoul-Washington alliance.

South Korea's presidential office said Flynn suggested that the two countries maintain close ties on key security issues.

Kim also congratulated US President Donald Trump for his inauguration and said South Korea wishes to keep thorough cooperation with the new Washington administration, especially on urgent issues, including North Korean nukes.

The phone conversation was arranged at the US' request.

Kim met Flynn in Washington ahead of Trump's inauguration, where the two agreed to continue making progress in the deployment of an advanced US missile defense system in South Korea, while maintaining a firm stance against Pyongyang's nuclear development.

In a related development, the Seoul government said South Korea's Ambassador for Public Diplomacy Cho Hyun-dong will visit the US Jan. 22-25 for meetings with officials of the Trump government. 

Representatives from South Korea and the United States who deal with inter-Korean affairs are expected to gather in Washington in the near future, a diplomatic source also said.

Kim Hong-kyun, special representative for Korean Peninsula peace and security affairs at South Korea's foreign ministry, is currently planning on visiting Washington to meet his counterpart Joseph Yun, the US special envoy for North Korea policy, the source said.

Yun, designated to the seat by former US President Barack Obama, maintains his post under the new administration of Donald Trump.

Political pundits said the meeting will reflect the Trump administration's stern stance on North Korea. (Yonhap)