ERBIL, Kurdistan Region of Iraq – Iran’s Permanent Representative to the United Nations (UN) on Wednesday drafted a letter to the UN Security Council threatening to withdraw from the nuclear Non-Proliferation Treaty (NPT) should UN sanctions be reimposed on Tehran over its nuclear program.

The move comes as the International Atomic Energy Agency (IAEA) mulls a US and E3 (France, Germany, and the United Kingdom) proposal that would condemn Iran for its failure to cooperate with the international watchdog.

The vote on the resolution at the IAEA’s week-long Board of Governors meeting in Vienna was scheduled to take place on Wednesday; however has been postponed to Thursday due to time constraints, according to Iranian state media.

Iranian Ambassador to the UN Saeed Iravani, in his letter, wrote that Iran would consider “proportionate responses” were the UN to sanction Tehran over the alleged non-compliance, saying that “starting the process of withdrawal from the NPT” would be on the cards.

Iravani added that, should this outcome be reached, “the responsibility for the consequences of such a shift will rest squarely with those who seek to misuse international mechanisms for narrow political ends.”

IAEA Director-General Rafael Mariano Grossi said Monday that the organization had “found man-made uranium particles at each of three undeclared locations in Iran” during inspections in 2019 and 2020, noting that “Iran has repeatedly either not answered, or not provided technically credible answers to, the [IAEA]’s questions. It has also sought to sanitize the locations, which has impeded Agency verification activities.”

The Atomic Energy Organization of Iran (AEOI) chief Mohammad Eslami told reporters in Vienna that Grossi’s report was “clearly biased and heavily politicized.”

The UN previously imposed sanctions on Iran before the Joint Comprehensive Plan of Action (JCPOA) agreement in 2015, with the landmark agreement seeing Iran receive sanctions relief in exchange for caps on its nuclear program. In addition to the US, the E3 countries played a salient role in the accord.

However, the US withdrawal from the JCPOA during President Donald Trump’s first term in 2018 and his subsequent campaign of “maximum pressure” on Tehran to force its foe to abandon its nuclear program has led to a lengthy standoff.

US and Iranian authorities are set to meet for a sixth round of nuclear negotiations in the Omani capital of Muscat on Sunday, Oman’s Foreign Minister Badr al-Busaidi said on Thursday.