The Republic of Korea (ROK) has sent a senior official to the US aiming to push for the "almost stalled denuclearization talks" between Washington and Pyongyang, Yonhap reported.
While Seoul has been eager to expand cross-border changes and reduce border tension with Pyongyang, the US insists sanctions remain in place until the denuclearization is completed.
The DPRK and the ROK have held talks on logistics under the agreement reached after the two leaders' meeting in Pyongyang in September. Meanwhile, the two sides are working to destroy 20 guard posts in the Demilitarized Zone aimed at reducing border tensions.
Last week, the South sent a gift of 200 tons of tangerines to the DPRK in return for Pyongyang's mushrooms.
The unification minister of the ROK Cho Myoung-gyon started a five-day trip to the US from Tuesday.
Yonhap said the joint projects between Seoul and Pyongyang have been faced with apparent opposition from the US, and Cho is likely to emphasize Seoul's argument that an improvement of inter-Korean relations could benefit the denuclearization process and ask the US to cooperate in easing sanctions on the cross-border projects.
Cho is likely to meet US Secretary of State Mike Pompeo, the agency reported.
On the US side, the Trump administration has insisted that the sanctions on the DPRK remain until a complete and irreversible denuclearization, and it will continue to push for the process.
On Tuesday, US President Donald Trump said he is fully aware of the DPRK's denuclearization in response to a media report saying Pyongyang has not declared more than a dozen missile sites.
"We fully know about the sites being discussed, nothing new - and nothing happening out of the normal," Trump wrote in a post on Twitter, referring to a report on Monday in the New York Times.
"I will be the first to let you know if things go bad!"
Last week, a scheduled meeting between Pompeo and senior DPRK official Kim Yong Chol was called off.
The meeting was due to be held in New York last Thursday aimed at paving the way for a second summit between Trump and DPRK's leader Kim Jong Un and at making progress on denuclearization.
