TEHRAN, April 23 (Xinhua) -- The activation sounds of air defense systems in Tehran and several other Iranian cities on Thursday evening were triggered by the presence of micro-aircraft and small drones, Iran's Fars News Agency reported.
The report, citing sources, said the detections occurred in multiple parts of the country and prompted defensive responses.
The report added that military experts attributed the activation of the air defense system during the Iran-U.S. ceasefire to factors such as patrols by "friendly aircraft" and system maintenance and upgrades. ■
