The head of Iran’s Atomic Energy Organization is not expected to attend the annual gathering of the UN nuclear watchdog’s member nations in Vienna for the first time in years because he is banned from international travel.

Axar.az reports, citing the AP, Mohammad Eslami’s exclusion from the IAEA conference is another sign of rapidly deteriorating relations between Iran and the West. The United States and Iran have resumed fighting, on and off, after a fragile ceasefire collapsed in July.

Austria sought a waiver of the travel ban on Eslami with the UN sanctions committee but it was not granted, the official said. The official wasn’t authorized to comment on the sensitive matter and spoke on condition of anonymity.

As host of the United Nations in Vienna, Austria can request exemptions from travel bans to enable sanctioned officials to attend international conferences at the UN.