United Nations Secretary General Antonio Guterres addresses the United Nations Security Council during a meeting, amid Russia's invasion of Ukraine, at the United Nations Headquarters in Manhattan, New York City, New York, U.S., April 5, 2022.
United Nations Secretary General Antonio Guterres addresses the United Nations Security Council during a meeting, amid Russia's invasion of Ukraine, at the United Nations Headquarters in Manhattan, New York City, New York, U.S., April 5, 2022. Reuters / ANDREW KELLY

The United States will again push for more U.N. sanctions on North Korea if it carries out a seventh nuclear test, despite opposition by China and Russia, U.S. Ambassador to the United Nations Linda Thomas-Greenfield said on Tuesday.

China and Russia last week vetoed a U.S.-led push to impose more U.N. sanctions on North Korea over its renewed ballistic missile launches, publicly splitting the U.N. Security Council for the first time since it started punishing Pyongyang in 2006.

Thomas-Greenfield has warned that North Korea is "actively preparing to conduct a nuclear test." If that happens, she said on Tuesday, the United States "absolutely will" push again for more U.N. sanctions on Pyongyang.

"First of all we need to enforce the sanctions that we have," she told reporters. "And we certainly - as we attempted in this last resolution - will push for additional sanctions."

Over the past 16 years, the Security Council has steadily, and unanimously, stepped up sanctions to cut off funding for Pyongyang's nuclear weapons and ballistic missile programs. It last tightened sanctions on Pyongyang in 2017.

Since then China and Russia have been pushing for an easing of sanctions on humanitarian grounds.