Linda Thomas-Greenfield, the United States ambassador to the United Nations, is scheduled to visit South Korea and Japan next week to discuss a wide range of issues, including Russia's recent exercise of its veto to extend the mandate of a panel of experts overseeing sanctions on North Korea, the US mission to the UN announced Monday.

The visit to the US' key Asian treaty allies, scheduled for April 14-20, comes at a crucial juncture, underscoring the pressing need to bolster bilateral and trilateral cooperation on the UN Security Council.

The imperative arises amid instances of nonconformity by Russia and China, both of which wield veto power as permanent members of the Security Council, particularly concerning pending issues pertaining to North Korea.

Thomas-Greenfield will "participate in engagements to advance bilateral and trilateral cooperation, on the United Nations Security Council and beyond" in both countries, the mission's spokesperson Nate Evans said in a statement.

The ambassador will meet South Korean and Japanese senior officials to discuss shared priorities on the UN Security Council.

Thomas-Greenfield will also "discuss next steps to ensure a continuation of independent and accurate reporting of the DPRK's ongoing weapons proliferation and sanctions evasion activities," Evans added, referring to North Korea by its official name, the Democratic People's Republic of Korea.

Russia exercised its veto power on March 28 to block the yearly extension of the panel of experts responsible for monitoring the enforcement of UN Security Council resolutions on North Korea. The 1718 Committee Panel of Experts also releases reports on cases that bypass UN sanctions twice a year.

China, one of the five veto-wielding permanent members of the Security Council, opted to abstain from the vote. Meanwhile, the remaining 13 members of the 15-member UN Security Council voted in favor of the extension, which has been continuously renewed since its establishment in 2009.

A senior official at the Foreign Ministry in Seoul, who wished to remain anonymous, said Tuesday that cooperation on the UN Security Council, including replacing the soon-to-be-defunct panel of experts, would be a key agenda item during Thomas-Greenfield's visit to South Korea from April 14 to 17.

South Korean Foreign Minister Cho Tae-yul also revealed that South Korea "was devising a new monitoring mechanism that can replace the panel of experts" with like-minded countries during his meeting with NATO Secretary-General Jens Stoltenberg on Friday, according to the Foreign Ministry in Seoul.

In South Korea and Japan, Thomas-Greenfield will reiterate the US commitment to addressing regional and global priorities in collaboration with its allies, Evans said.

Topics of priority include human rights, nonproliferation and disarmament, responsible use of artificial intelligence, peacekeeping, food security and the threats posed by North Korea's unlawful weapons of mass destruction and ballistic missile programs.

In South Korea, Thomas-Greenfield will travel to the Demilitarized Zone that separates the two Koreas and meet with young North Korean defectors. The visit is the first by a US ambassador to the UN in 7 years and 6 months since a previous visit in October 2016.

In Japan, the ambassador will meet with family members of Japanese citizens who were forcibly abducted by North Korea during the 1970s and '80s.