The people of western districts of Tehran, particularly areas near the headquarters of the Atomic Energy Agency of Iran (AEOI), were jolted on Friday [March 12] by a siren lasting 15 minutes.

"The siren test of the Atomic Energy Organization was carried out according to the organization's normal protocols on Friday morning and the automatic system's siren lasted for 13 minutes," AEOI spokesman Behrouz Kamalvandi told the Iranian Students News Agency (ISNA). Kamalvandi added that the drill took place every three or four months.

Official news agencies, including IRNA and IRIB News, reported that citizens had been informed by an AEOI text message that the alert system would be tested at midday. All other news outlets ran the same report.

On January 29 a siren in the western districts of Tehran led to speculation over Israeli aircraft, but Tasnim News Agency, which is affiliated to the Revolutionary Guards, quoted an "informed source in the armed forces" as saying that the siren "had nothing to do with aerial threats that could trigger the air defense system of the country." Nonetheless, a commercial Turkish plane (Turkish Airlines Flight 874) due to land at Tehran's International Imam Khomeini Airport changed course and flew to the Azerbaijani capital Baku where it landed. The change of course was never explained.

Some social media users have claimed they received an alert text message from the AEOI only after the siren started bellowing. They have posted videos from neighborhoods close to the AEOI headquarters where the siren was heard the loudest - including Shahrak-e Azmaysh, Gisha, and Amirabad neighborhoods.

Many claimed that they received the alert message several minutes after the siren sounded.  Some complained on social media that the exercise was at the weekend. "Are they so stupid as to leave their test for a Friday morning to startle people from sleep…or is there something else, as it looks so highly likely," one tweet speculated.