The United States blocked Iran's top nuclear official from attending this week's International Atomic Energy Agency General Conference in Vienna. Iranian Atomic Energy Organization head Mohammad Eslami had been scheduled to address the annual meeting of member states that opened Monday.

Austria revoked Eslami's visa after originally granting one. Tehran protested the move at the conference opening, calling it a serious breach of its rights as an IAEA member. Iranian officials accused the United States of bullying and said a lower-level delegation member might still speak later in the week.

The United States objected to an exemption from U.N. sanctions reimposed through the snapback mechanism. Eslami is among those targeted by sanctions originally lifted under the 2015 nuclear deal. U.S. Ambassador Preston Wells Griffith III said the objection led the U.N. Security Council sanctions committee to deny the request.

U.S. Energy Secretary Chris Wright confirmed the administration opposed the travel. He stated that sanctioned individuals should not evade restrictions and that Eslami's participation would allow Iran to use the proceedings for propaganda while avoiding substantive cooperation on nuclear safeguards.

The decision comes amid a prolonged standoff. The IAEA has reported no verification access to Iran's key nuclear sites for more than a year. Iran suspended cooperation with inspectors in 2025 after a board resolution on safeguards compliance. The agency has described itself as completely blind to aspects of Tehran's program.

Iranian senior official Behrouz Kamalvandi denounced the block as malicious and said it sets a troubling precedent. Russia also criticized Austria's decision as a violation of host country obligations.

The IAEA General Conference continues through Friday in Vienna.