The U.S. will push for new international sanctions against North Korea if the country conducts a seventh nuclear test as anticipated, Washington’s ambassador the U.N. said Tuesday, while slamming China and Russia for vetoing a sanctions resolution last week.

At a press conference in New York, Linda Thomas-Greenfield said the U.N. Security Council (UNSC) has failed to hold the DPRK responsible for violating multiple U.N. resolutions, and that the UNSC’s “silence” will encourage Pyongyang to “test the will of the Council.”