Linda Thomas-Greenfield, U.S. ambassador to the United Nations, speaks during a press conference at the American Diplomacy House in Seoul, Wednesday. Yonhap

Ongoing discussions among like-minded nations to establish a new monitoring mechanism on North Korea's sanctions evasion could proceed without involving China and Russia, according to Linda Thomas-Greenfield, U.S. ambassador to the United Nations.

Her remarks came as South Korea, the United States and Japan have been accelerating efforts to find a new alternative for the soon-to-expire U.N. Security Council (UNSC) expert panel, prompted by Russia's veto and China's abstention in the annual renewal vote in March.

"I don't expect that they (China and Russia) will cooperate or agree with any efforts that we make to find another path, but that is not going to stop us from finding a path moving forward," she said during a press briefing at the American Diplomacy House in Seoul, Wednesday.

The envoy anticipated Moscow and Beijing to attempt to block efforts to establish the new monitoring mechanism on Pyongyang, especially considering that Russia has already violated the international sanctions imposed on North Korea.

"They are already engaging in trade with the DPRK. They are purchasing weapons against Security Council resolutions, and they — along with China — continue to protect the DPRK from being held accountable," she said, referring to North Korea by its official name, the Democratic People's Republic of Korea.

The press conference took place on the final day of her four-day visit to Seoul, during which she held separate meetings with President Yoon Suk Yeol, Foreign Minister Cho Tae-yul and Defense Minister Shin Won-sik.

This marked Thomas-Greenfield's first visit to South Korea in her 40-year diplomatic career and the first trip 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. The UNSC expert panel, which has been overseeing sanctions enforcement against North Korea for the past 15 years, is set to expire at the end of April after Russia vetoed the annual renewal of the panel's mandate in a routine UNSC resolution vote last month, with China abstaining.

Against this backdrop, the ambassador's talks with South Korean officials focused on enhancing cooperation to ensure the continued accurate reporting on the implementation of sanctions on North Korea.

Linda Thomas-Greenfield, center, U.S. ambassador to the United Nations, poses with U.S. Forces Korea Commander Gen. Paul LaCamera, second from left, and soldiers stationed at the Demilitarized Zone (DMZ) separating the two Koreas during her visit to the DMZ, Tuesday. Joint Press Corps

Wrapping up her visit, Thomas-Greenfield stated that various options on the form of the new monitoring body are under discussion with Asian partners. The envoy departed for Japan hours after the press conference.

"We discussed options both inside and outside the U.N. system in lockstep with our Republic of Korea and Japanese partners," she said, referring South Korea by its official name.

"We will continue to have these conversations in the days and weeks ahead, because it's critical that all member states continue receiving independent and accurate reporting of the DPRK's ongoing weapons, proliferation and sanction evasion activities."

Thomas-Greenfield dismissed skepticism regarding the effectiveness of international sanctions in deterring North Korea's weapons ambitions.

Sanctions on North Korea were first imposed in 2006 and subsequently strengthened in response to its continued weapons development. However, contrary to their intended goal, the reclusive regime has not abandoned its nuclear ambitions, but rather made progress in nuclear arms development.

"If they (sanctions) didn't work, countries wouldn't have constantly complained about them. The DPRK does not want sanctions because they know the sanctions have hampered their ability to accomplish their goals," she said.