Reports are emerging of a possible attack on a military facility in the city of Karaj on Thursday night, at a moment tensions are boiling between Tehran and Israel over the Islamic Republic’s advancing nuclear program.

The BBC’s Persian-language service reported that widespread gunshots and and explosions were observed in the area, which lies just west of the Iranian capital. Anti-aircraft fire was also seen in multiple circulating clips, which remain unverified. 

این ویدیو که گفته می‌شود امشب در منطقه عظیمه کرج گرفته شده به دست بی‌بی‌سی رسیده است.
دقایقی پیش برخی کاربران شبکه‌های اجتماعی در کرج از شنیده شدن صدای شلیک ممتد و انفجار خبر داده‌اند.
برخی شاهدان گلوله‌های شلیک شده را به پدافند ضدهوایی تشبیه کرده‌اند. pic.twitter.com/Foo3uerDl9

— BBC NEWS فارسی (@bbcpersian) February 23, 2023

However, the Iranian government is denying that it was a hostile attack from a foreign force, instead calling it a live-fire defense exercise. 

Iran’s official Islamic Republic News Agency tweeted a video describing military training in the area. 

Israeli media has also picked up on the claims of an attack, while noting that a key nuclear facility is located in Karaj. As The Jerusalem Post recounts: 

Defense facilities in and near Karaj have been targeted by attacks repeatedly in recent years.

In July 2021, Iran blamed Israel for a sabotage operation that targeted a building belonging to Iran’s Atomic Energy Organization (IAEO) in Karaj the month before.

#BREAKING: explosion and antiaircraft fire emerging over Karaj tonight in #Iran. pic.twitter.com/T8RSxRmaYl

— Jason Brodsky (@JasonMBrodsky) February 23, 2023

One journalist and observer of the region described that “An unofficial report circulating online says that a depot of IR-6 centrifuges in Kondar village, 24 km from Karaj, Alborz province, was targeted Thursday night.” However, there’s no independent confirmation of this, despite the widely circulating videos.

Bloomberg reported Sunday that Iran has currently reached an 84% uranium enrichment level, a new high. While Iran has all long claimed it is only for peaceful nuclear energy purposes, the number needed for achieving an atomic bomb is 90%.