High-resolution satellite images recently captured reveal how Iran has covered the entrances to tunnels at the Isfahan nuclear complex with soil, according to the Institute for Science and International Security.

The central and southern entrances are now completely unrecognizable and fully buried. The northern tunnel entrance, which features additional defensive measures, has also been filled with soil. There is no longer any vehicle activity around any of the three entrances.

It appears clear that the Iranians are very concerned about a potential airstrike or a U.S. or Israeli raid on this heavily fortified nuclear facility. Covering the tunnel entrances will reduce the effectiveness of any possible air attack and make a ground assault by special forces aimed at seizing or destroying any highly enriched uranium inside much more difficult. It is also possible that Iran has moved equipment or materials into the tunnels for protection, although this cannot be confirmed. Preparations like these were last observed in the days leading up to the "Midnight Hammer" operation, which targeted facilities in Fordow, Natanz, and Isfahan.

Image 1: Overview of the tunnel entrances leading to the underground complex in Isfahan. All three tunnel entrances have been filled with soil.

Images 2 and 3: Above is a view of the central tunnel entrance. Any potential facility openings and the tunnel entrance itself have been completely buried. Below is a view of the southern tunnel entrance. Additional soil has been added on top, fully covering the entrance.

Image 4: View of the northern tunnel entrance. It has now been filled with soil, completely sealing the inner entrance.