The Republic of Korea and the United States will in early April start a joint military exercise that was postponed because of the Winter Olympics and Paralympics, an ROK presidential security adviser said, according to the ROK's Yonhap news agency.

Moon Chung-in, speaking at a seminar in Washington, said he is "aware the drills will begin in the first week of April", Yonhap reported on Wednesday.

"However, if there are talks between the United States and North Korea before the drills there may be some kind of compromise," the adviser added, saying he hopes for dialogue between Pyongyang and Washington to begin.

On Sunday, the ROK's presidential Blue House said the Democratic People's Republic of Korea's high-level delegation was "willing to have talks" with the US.

The US welcomed the talks and said it is open to discussions with the DPRK, but only to convey the US stance that it must give up its nuclear and missile programs.

Li Chengri, an expert at the Chinese Academy of Social Sciences, said for a long time the DPRK has expressed its strong dissatisfaction with the ROK-US joint military exercise and considered it a dangerous move against the DPRK.

"The DPRK believes that stopping the joint military exercises is necessary for dialogue," Li said.

The drill will surely stimulate DPRK's nerves and will inevitably bring about adverse effects on the thaw in the Korean Peninsula since the Winter Olympics, Li said, adding that Pyongyang will not sit idle if the US and the ROK push ahead with the postponed exercises.

DPRK's official KCNA news agency said on Monday that restarting the drills would be an "act of ruthlessly trampling even a small sprout of peace that has been now seen on the Korean Peninsula".

The US and the ROK usually hold their Key Resolve and Foal Eagle exercises in March and April, which can involve as many as 17,000 troops from the US and over 300,000 from ROK.

US State Department spokeswoman Heather Nauert said she had "no reason... to believe that we wouldn't restart some of our exercises that we do", Reuters reported.

"We've done those for many decades," Nauert added at a news conference.

The ROK's Defense Minister Song Young-moon said earlier this month he and his US counterpart, Jim Mattis, would make an announcement on the drill plans between the end of the Winter Paralympics on March 18 and the start of April.

On Monday, Joseph Yun, the US special envoy for the DPRK policy, said he will resign from his post. According to Xinhua, US media said the departure of Yun, who has been supportive of solving the peninsula issue through dialogue, was due to his long disappointment over Donald Trump administration's provocations against the DPRK, and the absence of diplomats' voices in the government's decision-making process.