Iran’s mission to the United Nations welcomed Tuesday’s surprise resignation of US Ambassador Nikki Haley, one of the Trump administration’s most vocal opponents of the Islamic Republic.

“We do not know who she was or what she was about, but she was a serious problem at the UN with her uninformed statements & her causing the isolation of US,” Alireza Miryousefi, the mission’s press secretary, wrote on his Twitter account.

He also quipped “there is no new sheriff in town,” referring to remarks Haley made at the 2017 annual meeting of the pro-Israel AIPAC lobby.

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“For anyone that says you can’t get anything done at the UN, they need to know there’s a new sheriff in town,” she said at the time, promising to defend Israel and oppose Iran at the world body.

At the UN, Haley pushed member states to enforce US sanctions on Iran as part of President Donald Trump’s withdrawal from the 2015 nuclear deal and also criticized its missile program and support for armed groups in the Middle East.

In one noticeable instance, Haley gave a press conference in front of missile parts she said were provided to Yemeni rebels by Iran, a charge denied by Tehran.

Gholamali Khoshroo, Iran’s envoy to the UN, said Tuesday the US’s isolation in the international community had increased during Haley’s tenure because of the US pursuit of unilateralism, according to state-run media.

The report on the IRNA website described Haley as “one of the anti-Iranian figures of the United States government, [who] has always taken strong stance against Iran.”

Khoshroo also said that Haley had failed to push the world away from supporting Palestinians.

Iran’s comments ran in stark contrast to reactions from politicians in Iranian arch-enemy Israel, where the US envoy was widely praised for her defense of the Jewish state at the UN.

Haley’s departure was also met with words of praise from other Western countries, even those the envoy sparred with during her two-year tenure.

Despite her blunt talk and criticism of the UN, Secretary-General Antonio Guterres issued a message of “deep appreciation” for Haley after she announced she would step down at the end of the year.

Stephane Dujarric, Guterres’s spokesman, said the UN had yet to receive formal notification of her resignation as Washington’s permanent representative to the world body.

“The secretary-general wishes to express his deep appreciation for the excellent cooperation and support that Ambassador Haley has always demonstrated,” he said.

“They had a very productive and strong working relationship during her tenure as United States permanent representative.”

Haley announced her unexpected decision at the White House with US President Donald Trump.

She gave no reason for the move or what her next step would be except to say she did not plan to run in 2020 and would campaign for Trump’s reelection.

At the United Nations, she was a vocal defender of Trump’s “America First” foreign policy, which has challenged multilateral approaches to the world’s biggest problems.

She has pushed strongly for reform of the UN, which the Trump administration sees as bureaucratic and wasteful.

During her tenure, the United States broke with traditional UN positions on the Palestinians, withdrew from UNESCO and cut funding to the UN agency for Palestinian refugees, and abandoned the UN Human Rights Council as biased against Israel.

Britain’s ambassador to the United Nations, Karen Pierce, told AFP she was “very disappointed” by Haley’s resignation, which she said learned through media reports.

France’s ambassador, Francois Delattre, praised Haley as one of the US administration’s “most talented” officials.

Despite some disagreements, he said, “we established a working relationship that was particularly close and trusting.”

Ashish Pradhan, an expert with the International Crisis Group, said Haley’s departure raised the prospect of an even more hawkish replacement.

“The fear now is whether the person who replaces her will take an even tougher line against the UN, especially with National Security Adviser John Bolton now in the White House,” he said.