Nikki Haley, the U.S. ambassador to the United Nations, on Monday accused Russia of systematically “cheating” on international sanctions against North Korea by illicitly helping the country acquire oil and coal.

Three months after President Trump held a summit with Kim Jong Un in Singapore, Haley told the U.N. Security Council that Moscow has been “actively working to undermine Security Council sanctions” imposed on North Korea.

“Why after voting for sanctions 11 different times is Russia backing away from them?” she said. “We know the answer. It’s because Russia has been cheating. And now they’ve been caught.”

Haley spoke at an emergency meeting of the Security Council called by the United States. Repeating an accusation she made last week, Haley said Russia had threatened to block an independent report on the status of North Korean sanctions unless a list of Russian violations was excised.

Russian ambassador Vassily Nebenzia denied that Russia had violated sanctions or blocked the report.

“This is a falsehood,” he said, according to the official translation of his remarks.

Citing Russia’s actions in Syria, the alleged poisoning of a former spy in Britain and election interference in the United States, Haley said, “Deny, distract and lie” is “the new norm of Russian culture.”

Haley’s remarks represented another example of administration officials using uncompromising rhetoric against Russia even as Trump has played up his friendly relationship with President Vladi­mir Putin.

Trump also has exchanged warm regards with Kim, even though negotiations to curb North Korea’s nuclear and ballistic program have been stalemated. Last month, Trump canceled Secretary of State Mike Pompeo’s planned visit to Pyongyang, hours before the diplomat was due to leave, because Trump felt the talks were not making “sufficient progress,” he tweeted.

The United States is trying to maintain what officials call the “maximum pressure” campaign of North Korean sanctions, although Trump has said he longer uses the term “because we’re getting along.”

The administration led efforts last year to dramatically increase wide-ranging sanctions against North Korea to dry up its revenue for missile and nuclear programs.

But Haley said the United States has evidence that Russia has been evading the measures by helping with ship-to-ship transfers of oil, coal and other goods.

“Step by step, sanction by sanction, and time and time again, Russia is working across the board to undermine the sanctions regime,” she said.

Nebenzia accused the U.S. administration of undercutting diplomatic overtures by refusing to make any concessions to Pyongyang, only demands. And he said the White House is being overly aggressive in the Security Council in an attempt to “subjugate” the body to U.S. policy.

China’s ambassador Ma Zhaoxu said “confrontation is a dead end” and called for U.N. sanctions to be enforced but gradually lifted as a reward for steps toward denuclearization.

Last month, Trump tweeted that “China is providing North Korea with considerable aid, including money, fuel, fertilizer and various other commodities. This is not helpful!”

In a briefing to the council, U.N. political affairs chief Rosemary A. DiCarlo warned that despite some positive steps, “there continue to be signs the DPRK [North Korea] is maintaining and developing its nuclear weapons and ballistic missile programs.”