North Korean leader Kim Jong-un guides a target-striking contest of the special operation forces of the Korean People's Army to occupy islands in Pyongyang on Aug. 25, 2017.

Secretary of State Mike Pompeo said Wednesday that denuclearization negotiations with North Korea will be completed by January 2021.

The deadline reflects a commitment from North Korean dictator Kim Jong Un, according to Pompeo.

The chief U.S. diplomat's statement came a day after South Korean President Moon Jae-in and North Korea's Kim met in Pyongyang to discuss the next steps in their peace process. It also marks the latest significant development in President Donald Trump's outreach to Kim following a much-hyped summit in Singapore earlier this year.

The Pentagon said it is continuing to back the State Department's efforts on North Korea.

"The Department of Defense remains in full support of our diplomats as they work to achieve the final, fully verified denuclearization of the DPRK as agreed to by Chairman Kim," U.S. Marine Corps Lt. Col. Christopher Logan said in an emailed statement to CNBC.

The White House did not immediately respond to CNBC's request for comment.

While Trump has taken center stage along with Kim in the ongoing peace process, experts point to the effect South Korea's president has had on the negotiations.

"I think we can call the recent efforts by South Korea the Moon miracle," Harry Kazianis, director of defense studies at the Center for the National Interest, told CNBC.

"South Korea's president deserves tremendous credit for doing what looked like the impossible, as talks between the U.S. and North Korea were headed for a dead end. I think it is clear there is the possibility of a compromise and even another Trump-Kim summit, right before the midterms," he added.

Read Pompeo's full statement below:

On the Outcome of Summit Meeting between President Moon and Chairman Kim

The United States congratulates President Moon Jae-in and Chairman Kim Jong Un on the successful outcome of their summit meeting in Pyongyang. We welcome President Moon and Chairman Kim's reaffirmation of the Singapore joint statement of complete denuclearization of the Korean Peninsula, including the permanent dismantlement of all facilities at Yongbyon in the presence of U.S. and IAEA inspectors. We also welcome Chairman Kim's decision to complete the previously announced dismantlement of the Tongchang-ri site in the presence of U.S. and international inspectors as a step toward the final fully verified denuclearization of North Korea, as agreed by Chairman Kim at the Singapore summit with President Trump. On the basis of these important commitments, the United States is prepared to engage immediately in negotiations to transform U.S.-DPRK relations. This morning, I invited my counterpart Foreign Minister Ri Yong Ho to meet in New York City next week where we are both already scheduled to be in attendance at the United Nations General Assembly meeting. Likewise, we have invited North Korean representatives to meet our Special Representative for North Korea, Stephen Biegun, in Vienna, Austria at the earliest opportunity. This will mark the beginning of negotiations to transform U.S.-DPRK relations through the process of rapid denuclearization of North Korea, to be completed by January 2021, as committed by Chairman Kim, and to construct a lasting and stable peace regime on the Korean Peninsula.

The latest revelation comes a little more than three months after the reclusive leader from the North sat down for the first time with Trump to discuss denuclearization.

A month after the meeting, the top U.S. military commander on the Korean peninsula said that the material needed for North Korea to make nuclear bombs is still intact.