Russia is “actively working to undermine” international sanctions on North Korea, a top U.S. diplomat charged on Monday, calling the activities “systematic” and not “one-offs.”

U.N. Ambassador Nikki Haley’s allegation during a Monday session came amid a dispute over a report from an independent panel of U.N. experts. The original report, she said, chronicled sanctions violations by Russian entities that were edited from the public document at the behest of the Russian government. But that controversy is the culmination of other behind-the-scenes fights that have prevented international monitors from blacklisting violators of North Korea sanctions.