The United States is in behind-the-scenes talks with the Democratic People's Republic of Korea (DPRK) over a possible third summit and has proposed working-level negotiations, Republic of Korea (ROK) President Moon Jae-in said in written answers to questions posed by visiting foreign journalists on Wednesday.

He stressed that there is no reason to talk of a "stalemate" just because there had been no official dialogue, aimed at the denuclearization of the DPRK.

"Both sides have been engaged in dialogue in regard to a third summit," Moon said.

"It's noteworthy that the behind-the-scenes talks have been preceded by the mutual understanding of each other's position gained through the Hanoi summit," he added. 

U.S. President Donald Trump and DPRK's leader Kim Jong Un held their second meeting in the Vietnamese capital of Hanoi in February but failed to reach a deal due to differences between U.S. calls for denuclearization and DPRK's demands for relief from sanctions. 

The U.S. had made a proposal for working-level talks, Moon said, urging the DPRK to return to the negotiating table "at the earliest date possible." 

There are no details on when and how the U.S. proposals were made. 

"The resumption of negotiations between the DPRK and the U.S. will take it to the next level. I believe everything has now fallen into place for that to happen," Moon said. 

"By responding to the U.S. proposal for working-level negotiations, it can also show its determination to denuclearize," he noted. 

U.S. Secretary of State Mike Pompeo said on Sunday that a recent exchange of letters between Trump and Kim boosted hopes for a restart of talks, calling it a "very real possibility." 

Kim receives letter with 'excellent, interesting' content from Trump: KCNA 

Trump says he received a 'beautiful letter' from DPRK's Kim 

Last week, the White House extended six executive orders containing sanctions imposed over DPRK's nuclear and missile programs by one year. 

Pyongyang's media said on Wednesday that the decision is an act of hostility and an outright challenge to an historic summit between the two countries in Singapore last year.

Stephen Biegun, the U.S. special envoy for DPRK who led working-level talks ahead of the Hanoi summit, is visiting Seoul from Thursday for meetings with ROK officials before joining Trump, who is due in the ROK this weekend. 

Trump is considering visiting the demilitarized zone separating the ROK and the DPRK, where Kim and Moon had their historic first summit last year, an ROK official said. The two sides are technically still at war after their 1950-53 conflict ended in a truce, not a treaty. 

A U.S. senior administration official said on Monday that the president has no plans to meet with Kim when he travels to the ROK over the weekend after attending a G20 summit in Japan.

A symposium on the Korea peace process will be hosted by Yonhap in Seoul on Thursday. 

Commenting on Moon's remarks, Chinese Foreign Ministry spokesperson Geng Shuang said that China hopes the U.S. and the DPRK will keep up the momentum of dialogue and contact, and meet each other half way.

"Our position is consistent. China is willing to work with the two sides and other concerned parties to push forward the political settlement process on the Korean Peninsula issue," Geng said during a regular press conference on Wednesday in Beijing.