President Yoon Suk Yeol poses with U.S. Ambassador to the United Nations Linda Thomas-Greenfield during a meeting at the presidential office in Seoul, Monday. Courtesy of presidential office

President Yoon Suk Yeol highlighted South Korea's steadfast commitment to upholding U.N. sanctions on North Korea during a meeting with U.S. Ambassador to the United Nations Linda Thomas-Greenfield in Seoul, Monday.

The meeting, which took place during the U.S. envoy's visit to South Korea, indicates increased collaboration between Seoul and Washington in establishing a new monitoring mechanism for North Korea. This effort is crucial as North Korea seeks to circumvent international sanctions, especially with the soon-to-expire U.N. monitoring body.

Thomas-Greenfield arrived in Seoul on Sunday for a four-day visit, with a primary focus on enhancing bilateral cooperation concerning North Korea amid heightened concerns over the modernization of Pyongyang's arms program, particularly given its burgeoning military partnership with Russia.

During the meeting, Yoon stressed the importance of enhancing cooperation within the United Nations Security Council (UNSC) to ensure compliance with sanctions imposed on North Korea by both Pyongyang and other member states, according to the presidential office.

In response, the U.S. envoy expressed full support for Seoul's efforts to deter Pyongyang's nuclear and missile development and promote human rights in North Korea.

Thomas-Greenfield also held separate talks with South Korea's foreign and defense ministers on the same day.

During her meeting with Defense Minister Shin Won-sik, the envoy expressed concerns about the impending disbandment of the U.N. expert panel.

She highlighted the potential for this disbandment to create gaps in the implementation of sanctions on North Korea, which Pyongyang might exploit as opportunities for further nuclear and missile advancements, according to the defense ministry.

Defense Minister Shin Won-sik, left, poses with U.S. Ambassador to the United Nations Linda Thomas-Greenfield during a meeting at the Ministry of National Defense in Seoul, Monday. Courtesy of Ministry of National Defense

The envoy also called on South Korea to join U.S. efforts to come up with alternative measures to ensure the continued issuance of reliable reports on violations of the sanctions on North Korea. In response, Shin said Seoul will continue to strengthen cooperation with the U.N. and Washington in the future to ensure the implementation of U.N. Security Council resolutions.

Before visiting the defense ministry, Thomas-Greenfield also held talks with Foreign Minister Cho Tae-yul.

During the remaining days of her stay, the envoy plans to visit the Demilitarized Zone (DMZ) separating the two Koreas and meet young North Korean defectors, before departing for Japan on Wednesday.

Her trip marks the first visit to Seoul by a U.S. ambassador to the U.N. since 2016.

The rare visit of the American envoy comes amid escalating concerns regarding the weakening of international efforts to restrain Pyongyang's nuclear weapons program, with just two weeks left until the UNSC panel of experts terminates its operations.

U.S. Ambassador to the United Nations Linda Thomas-Greenfield leaves the Ministry of Foreign Affairs in Seoul, Monday, following her meeting with Foreign Minister Cho Tae-yul. Yonhap

The panel, created in 2009, has been submitting reports biannually to the UNSC, recommending actions to enhance the implementation of sanctions on North Korea first imposed in 2006 and subsequently strengthened in response to its continued weapons development.

However, Russia vetoed the annual renewal of the panel's mandate in a routine UNSC resolution vote last month, with China abstaining. Without the resolution, the panel will cease to exist on April 30.

In other words, the sanctions will still be in force, but the eight-member experts group set up to monitor violations will be disbanded.

South Korean Ambassador to the U.N. Hwang Joon-kook has been vocal in condemning Russia's veto, likening it to "destroying a surveillance camera to avoid being caught red-handed." In a U.N. General Assembly meeting last week, he called for the need for alternative measures to uphold sanctions enforcement.

Earlier this month, Cho called for cooperation from NATO members during his visit to Brussels for a NATO meeting of foreign ministers.

During a meeting with NATO Secretary-General Jens Stoltenberg, Cho stated that South Korea is collaborating with like-minded nations to establish a new monitoring mechanism against North Korea. He also urged cooperation on Seoul's efforts to convene a U.N. General Assembly meeting to condemn Russia's veto.