Comprehensive Imagery Report on Nuclear Enrichment Related Sites, Post

Following the ceasefire between Iran, the United States and Israel established in early April 2026, we have continued to monitor key sites related to Iran’s nuclear program. In this report, we take a close look at key sites related to uranium enrichment, which include Esfahan, Fordow, and Natanz, the two separate mountain tunnel facilities south of the Natanz site, as well as centrifuge production sites. Several of these sites have shown signs of activity. While the activity visible in imagery is not conclusive, collectively, they indicate the following:

It is important to remember that an enrichment capability requires significantly more than the existence of UF 6 and centrifuges or centrifuge parts. Thus, the existence of the enriched uranium or centrifuge-related items should not be confused with Iran’s ability to enrich uranium, a capability not now existing in Iran. Another common misinterpretation is to confuse the HEU stock with building nuclear weapons, a process that has been significantly lengthened by the damage wrought by the two wars. Removing or downblending the HEU may be necessary for a nuclear deal, but the HEU’s presence in Iran does not mean that Iran is enriching uranium or building nuclear weapons. This HEU was there before the June war, coupled with a nuclear weapons program that could produce a weapon in months. Today, that timeline is at least a year. Moreover, moving technically to build that weapon is now fraught with risks and potential technical hurdles that could result in failure.

Esfahan Nuclear Complex

The Esfahan Nuclear Complex was largely untouched during this phase of the war, although a nearby defense site was targeted and destroyed. No attempt to dig into the tunnels or remove the physical barriers on the roads leading to the tunnel entrances has been observed as of May 17, 2026 (see Figure 1). Based on IAEA statements to the media, the tunnels reportedly hold over half of Iran’s stock of 60 percent HEU, estimated as 265 to 287 kilograms. [1] The tunnel is also believed to hold the Isfahan Fuel Enrichment Plant. During April and May 2026, Iran could be seen building revetments near the roads leading to the tunnel entrances. These serve as shelters for military equipment for ground and/or short-range air defense related purposes. [2]

Figure 1. A May 17, 2026, view of the tunnel entrances to the underground complex at Esfahan. The tunnel portals remain backfilled with dirt, blocking any external access.

Natanz Nuclear Complex

The above ground Natanz Nuclear Complex continues to show signs of widespread destruction, including several destroyed buildings and debris strewn throughout the complex. Overall, very little repair work and cleanup activity have been observed. No notable activity could be seen near the destroyed personnel entrances.

The Natanz site may hold up to approximately 74 to 96 kilograms of HEU, based on IAEA statements to the media and a process of elimination (see Esfahan and Fordow sections). It is not known publicly if the HEU is in the Natanz FEP or the adjacent tunnel complex.

Iran has moved and cleared some of the debris around the main entrance gate, which is necessary to enable vehicle access to the complex. The primary and backup electricity infrastructure remains destroyed, and chillers used in the HVAC system remain dispersed throughout the complex.

Imagery from May 2nd showed a small number of vehicles inside the complex, with at least one vehicle active near the above ground medical center. The medical center is located adjacent to the underground vehicle entrance building, which was destroyed at the onset of this 2026 phase of the war. By May 23rd, at the vehicle entrance some debris shifted around and a large object outside of the entrance building was removed, indicating activity. See Figure 2.

Since the June 2025 war, Iran is believed to have used the undestroyed portions of the underground Fuel Enrichment Plant to store enriched uranium, intact centrifuges, components, and equipment. It is not possible to determine the number of intact centrifuges or usable parts potentially stored at Natanz. A rough upper bound on intact centrifuges can be derived. Based on Iran’s declarations to the IAEA cascade installation at the FEP, as of June 2025, Iran could have had 1000 IR-4 centrifuges waiting to be installed as of June. It is not clear to what extent Iran would have been able to sort the remaining inventory or establish ad-hoc lighting and climate control, thus, “storage” may be a euphemism. In any case, it is largely inaccessible for the time being, and resumption of regular operations is out of the question given the lack of electric supply and industrial cooling at the site. Thus, there are no indications that Iran is reconstituting uranium enrichment activities at the FEP.

Figure 2. Above is a May 3, 2026, view of Natanz showing activity. Debris was cleared around the main entrance gate and an internal security checkpoint. Near the medical center, a vehicle can be seen. Below, a close-up of the vehicle entrance showing that some debris and objects have either been removed or shifted in place, indicating activity.

Pickaxe Mountain Site

The Pickaxe Mountain facility under construction just south of the Natanz Nuclear Complex showed continued activity. Satellite imagery from April and May 2026 showed a constant presence of vehicles moving around the construction site, indicating that the site remained under construction and work was progressing. Imagery from April 22, 2026, showed that Iran had partially backfilled the eastern tunnel portals with dirt, effectively restricting ground vehicle access from entering the tunnel portals. As of May 2, the western tunnel portals remained open and have not been backfilled with dirt. Overall, this tunnel complex does not appear to be operational or of paramount importance to the Iranians yet. That may help explain why neither the United States nor Israel has attacked the site so far. See Figure 3.

The smaller tunnel complex within the Pickaxe Mountain perimeter remained sealed, as of mid-May. The contents that led to the sealing are not known publicly. They could be enriched uranium or centrifuges. Alternatively, Iran may just be seeking to limit potential damage to a tunnel complex long associated with the Natanz enrichment site.

Figure 3. The eastern tunnel portals at Pickaxe Mountain can be seen partially filled with dirt.

This section was previously published in a standalone report but is included in its entirety to ensure the comprehensiveness of this report. [3]

Recent reporting of enrichment related reconstruction activities and of significant amounts of highly enriched uranium ( 80 kg) at the Fordow enrichment plant [4] led us to look more broadly at the site, which includes the well-known underground enrichment plant (bombed by the United States in June 2025) and the less-known above-ground support area north of the underground site (see Figure 4). As of mid-May 2026, available satellite imagery does not provide evidence of renewed access to, or reconstruction activity at, the underground Fordow enrichment plant itself. However, Iran appears to have recently increased passive defense measures at the site. Activity is also notable at the support site, which was barely damaged in attacks during either 2025 or 2026 attacks. The activity visible in satellite imagery is inconclusive. Open-source information on a specific building at the Fordow support site (which, although attacked, appears largely intact) suggests that it may house a relatively small hall containing gas centrifuges, installed for stable isotope enrichment, but also usable for uranium enrichment under certain conditions.

Destroyed Underground Enrichment Plant. The June 2025 bombing of the underground site largely destroyed it. Recent reporting states that up to 80 kilograms of 60 percent enriched uranium (HEU) are in the underground Fordow complex, although this value and its location have not been officially publicly confirmed and the IAEA has not conducted inspections of the site since before the June 2025 phase of the war.

At the underground Fordow enrichment plant, all four tunnel entrances leading to the enrichment plant under the mountain remain buried as of mid-May 2026 (see Figure 5). However, between May 10 and May 18th, Iran added passive defensive measures in the form of earthen/rocky mounds and other objects on the roads leading to the tunnel entrances. See Figure 6. The alternate placings of the piles/objects are very precise, which creates a series of chicanes, indicating they are not intended as obstructions, but rather as a means to prevent rapid ingress and egress by any vehicles (i.e., hindering offensive forces once onsite). The chicanes can be overcome by navigating around them but would ultimately need to be removed using earth moving equipment, slowing down an offensive and giving Iran additional time to respond. The placement indicates that Iranians still want access onsite for themselves, given the choice of chicanes rather than berms that fully block the roads, as were previously added on the roads leading to the Esfahan tunnel entrances. The fact that Iran added the defense measures, using time and resources, indicates that there is something at the destroyed enrichment plant worthy of recovery efforts, and Iran may have inadvertently revealed which path it deems most feasible by placing most of the chicanes on the road leading up to the single eastern tunnel portal. This portal may have been the least damaged, or it may be closest to an underground storage location of enriched uranium. As of May 26, Iran appears to have removed the chicanes leading to this specific entrance but kept the chicanes on the main road.

Vehicle activity was also present sporadically in the months before March; a December 31 image shows personnel vehicles (cars, maybe a van) parked outside the gate to the inner security perimeter of the tunnel entrances; a January 31 image shows at least four vehicles on the road to the main tunnel entrances and at least one vehicle and a truck along with an unidentified object on top of the slope near the site where one set of GBU-57 weapons entered the ventilation shafts of the facility (see Figure 7). Most images reviewed do not show vehicles near the underground enrichment plant, and specifically, no indication of earth being removed from the buried tunnel entrances. The reason for the activity near the impact holes is unclear given that the object cannot be identified. Perhaps, it is related to additional investigations or measurements, such as using a remote-controlled probe to assess the downshaft impact points. Activity within the immediate perimeter of the main vehicle entrances could also be related to the large above ground building adjacent to the main tunnel entrances, which holds utilities and serves other support functions. While no activity is seen directly at the building, the building was not attacked in 2025 or 2026 and appears to be entirely intact.

Vehicle activity is also present at the adjacent mountain, including in May 2026 (see Figures 8 and 9). The activity does not indicate tunneling or other earth moving activities, but the vehicle presence along the foot of the mountain, as well as at a nearby structure, is not conclusive. Post-June 2025, a new access path with no apparent purpose or end point was established leading up to and along parts of the mountain ridge. [5]

Above-Ground Support Area. Activity is also notable at the above-ground support area, which is two kilometers north of the underground site and has been an intrinsic part of the enrichment project since it was first being built as part of the Amad Plan, then called the Al Ghadir project. The above-ground support area remained largely untouched by both 2025 and 2026 attacks on Iran’s nuclear program. This site now shows relatively high levels of activity, as evidenced by vehicles around the site, as of mid-May (see Figure 10).

In terms of 2026 attacks on the Fordow site, we recently were able to identify an attack on the air defense site just north of the Fordow support site indicative of precise, but small, munitions used (see Figure 11). This air defense site was previously targeted during the June 2025 phase of the war, destroying anti-aircraft assets positioned there.

A large building constructed between 2019 and 2021 at the Fordow support site was also attacked in March 2026, but the clearly visible damage is limited to the roof and the rooftop equipment (see Figure 12). The strike occurred between March 18 to March 30. The extent of damage to the inside of the building is unclear; equipment on a section of the multi-level roof was destroyed, with char and debris visible on the roof, but whether the strikes penetrated the roof remains unclear (see Figure 13).

According to Iranian news sources and the Atomic Energy Organization of Iran (AEOI), the damaged building was inaugurated in April 2021 as the “National Research Center for Stable Isotopes Separation and Applications Development” (see Figure 14). [6] The facility has at least three distinct sections, consisting of “five thousand square meters, including eight workshops and eight laboratories. ” [7] The facility is visibly connected by overhead pipelines to the nearby Vacuum Technology Center and a utilities services building.

Part of the isotope separation planned for this facility reportedly involves gas centrifuges. This would be consistent with the layout of the facility seen during construction, Iran’s expressed desire to enrich iridium and tellurium, and Iran’s recent construction at Esfahan of iridium hexafluoride and tellurium hexafluoride production lines, the chemical compounds needed for gas centrifuge enrichment. It would also be consistent with scaling up pilot stable isotope enrichment activities, which Iran conducted in the Fordow enrichment plant in a dozen IR-1 centrifuges with Russia’s help from around 2017 until the setup was dismantled in January 2021. (The Joint Comprehensive Plan of Action provided for Iran to use two full cascades of around 350 IR-1 centrifuges for stable isotope production at the Fordow enrichment plant, but according to IAEA reports Iran only used a layout of up to 16 IR-1 centrifuges for this effort.)

For the enrichment of stable iridium 191 (Ir-91), one starts with the mixture of the two prominent stable isotopes, Ir-191 (37.3 percent) and Ir-193 (62.7 percent). Commercial producers of enriched iridium typically aim for a ratio of 80 percent Ir-191 and 20 percent Ir-193. [8] The cascade structure for iridium enrichment is different from uranium enrichment, but both types of cascades involve enrichment of the lighter isotope. Moreover, the cascades would start with a feed stock of 37 percent Ir-191, comparable to using already enriched levels of uranium as feed stock, such as 60 percent enriched uranium.

The opening of a “semi-industrial” production line for tellurium hexafluoride at Esfahan was announced in an AEOI post from February 2024. [9] In February 2025, Iran reported the opening of an iridium hexafluoride production line at Esfahan. Also in early 2025, Iran was discussing the finalization of the second stage of the Stable Isotope Separation Facility at Fordow, which reportedly involved gas centrifuges. [10]

A video of the construction process shows the facility includes a large hall 60 meters long, 18 meters wide, and 9 meters tall that does not appear to have been directly damaged by the March attack (see Figure 15). The hall has more than enough floorspace and height for two centrifuge cascades (roughly 350 centrifuges) of any of Iran’s centrifuge types deployed on a large scale before the June 2025 attacks, namely the IR-1, IR-2m, IR-4, and IR-6. Thus, it appears that centrifuges were or were to be installed in this large hall as of early 2025. Iran’s ability to deploy thousands of advanced centrifuges at Natanz and Fordow in the year prior to June 2025 indicates there was no shortage in centrifuges at that time, making it likely that Iran would have had a few hundred centrifuges available for this facility in early 2025. Determining whether the installation of centrifuges took place is critical. Once tellurium or iridium hexafluoride was introduced into the centrifuges, however, they would be unusable for uranium enrichment absent extensive sanitizing. If no iridium or tellurium hexafluoride was introduced, any installed centrifuge cascades would potentially be usable to enrich uranium. The status of the centrifuge installation or operation post-June 2025 is unknown.

The Vacuum Technology Center door was involved in making pressure transducers which are not a centrifuge component but key pieces of measuring equipment of the vacuum in a centrifuge enrichment plant. [11] They are used in large numbers and are difficult to make or procure internationally.

Synthetic aperture radar data collected by Copernicus’ Sentinel-1 satellite and analyzed and mapped by Bellingcat shows that additional surfaces underwent changes after March 2026, which could be indicative of damage inflicted (see Figure 16). The radar correctly identified damage inflicted on the defense site and the support area’s stable isotope building. Additional signatures seem to be false positives. Overall, there is less damage than expected at the support site given its importance for the operation of the underground centrifuge cascades in Fordow and a potential uranium enrichment site.

Figure 4. An overview of the underground enrichment plant in relation to the support area and the air defense site.

Figure 5. The four tunnel entrances to the underground enrichment plant remain buried as of May 10, 2026.

Figure 6. Between May 10 and May 18, Iran added earthen/rock mounds acting as chicane barriers along the roads inside Fordow. This May 22nd image provides a high resolution view of the barriers. The barriers are likely intended to prevent rapid ingress and egress by vehicles travelling between the backfilled tunnel entrances.

Figure 7. Above is a December 31, 2025, image of Fordow showing vehicle activity. Below is a January 31, 2026, of Fordow showing additional vehicle activity and also activity on the slope near the impact points of the GBU-57 weapons.

Figure 8. An overview of the Fordow mountain tunnel site and the adjacent mountain within the outer security perimeter.

Figure 9. Vehicle activity at the adjacent mountain site.

Figure 10. Vehicle activity around the support site as of May 18, 2026.

Figure 11. The attacked air defense site just north of the support area.

Figure 12. Above and below provide a close-up of the core building clusters within the Fordow support area, where the Stable Isotope Separation Center was attacked in March 2026.

Figure 13. A close-up of the facility pre- and post-strike, highlighting the damage inflicted on the roof of the building and the extensive rooftop equipment installed.

Figure 14. An AEOI poster displayed at the groundbreaking ceremony of the targeted building.

Figure 15. A view of the Stable Isotope Center and images of its construction taken from a video posted by the AEOI on Instagram. [1]

Figure 16. This image shows the surface changes post-March identified via Copernicus Sentinel-1 radar data, mapped by Bellingcat with Google Earth Engine. Source:

Centrifuge Production Sites

Centrifuge development and production sites remain destroyed, with no indication of reconstruction as of April/May 2026. In one case, an area tied to centrifuge manufacturing experienced additional destruction in the most recent conflict.

Natanz FEP. Denial of access to the Natanz FEP effectively denies Iran access to centrifuge components and manufacturing equipment that may remain there. While it is not known what components and associated machinery were inside the underground hall, it was reported in April 2022 that Iran had set up a “new workshop at Natanz for making parts for centrifuges [...] in one of the halls of the underground Fuel Enrichment Plant.” [1] It is not clear to what extent Israeli bunker busters caused damage to this hall; it is assumed to be the hall that was not holding enriching cascades of centrifuges, which was heavily attacked by both Israeli and US bunker busters.

Esfahan . Destruction remains visible as of May 17 at the above ground buildings at Esfahan believed to have held centrifuge manufacturing capabilities. The construction of a new roof noted post-June attacks was previously reported and we did not assess it as indicative of reconstructing capabilities at this location. [2]

TESA/TABA at Karaj . During the recent conflict, new damage was inflicted on the Karaj cluster of buildings associated with centrifuge manufacturing. [3] In June, Israel destroyed two buildings, where “different centrifuge components were manufactured,” according to the IAEA. [4] Satellite imagery subsequently showed three large workshop-type buildings destroyed. Post-June, limited clean-up and sorting of rubble can be seen at the site. Figure 17 shows the site before and after the recent strikes. It shows that as of April 25, 2026, one additional workshop and one additional unknown production facility, the latter with three "Chinese chillers," are visibly destroyed at the site. The attack also damaged a multi-story office building at the site. No new clean up or recovery efforts are visible as of that day.

Figure 17. Comparison of the Karaj centrifuge manufacturing site before and after the most recent attacks.

Kalaye Electric . There are no visible signs of reconstruction as of May 3, 2026, at the Kalaye Electric site, which was heavily destroyed in June 2025.

Tehran Research Center. According to the IAEA, in June 2025, “one building was hit where advanced centrifuge rotors were manufactured and tested.” [5] We have not been able to locate said building.

[1] David Albright, Sarah Burkhard, Spencer Faragasso, and Andrea Stricker, “Analysis of IAEA Iran Verification and Monitoring and NPT Safeguards Reports — June 2026,” June 9, 2026, Institute for Science and International Security, .

[2] Samuel Granados and Yeganeh Torbati, “Where is Iran’s Highly Enriched Uranium?,” The New York Times,

[3] David Albright, Sarah Burkhard, Spencer Faragasso, and the Good ISIS Team, “Recent Activity at the Fordow Enrichment Plant and its Associated Support Site,” Institute for Science and International Security , June 8, 2026,

.

[4] First reported by the Institute for Nuclear Security Studies (INSS) but not explained.

[5] David Albright, Sarah Burkhard, Spencer Faragasso, and the Good ISIS Team, “Comprehensive Updated Assessment of Iranian Nuclear Sites Five Months After the 12-Day War,” November 21, 2025, Institute for Science and International Security, .

[6]

[7]

[8] QSA Global, “What is the difference between natural and enriched Ir-192 sources?,”

[9]

[10]

[11] David Albright, Sarah Burkhard, Frank Pabian, and Jack Toole, “Conversion of Fordow: Another Unfulfilled Hope of the Iran Nuclear Deal,” July 10, 2019, Institute for Science and International Security, .

[12]

[13] “Iran set up centrifuge-parts workshop underground at Natanz, IAEA says,” April 24, 2026, Reuters, .

[14] David Albright, Sarah Burkhard, Spencer Faragasso, and the Good ISIS Team, “New Activity at the Esfahan Nuclear Complex,” Institute for Science and International Security, January 29, 2026, .

[15] Also reported by the IAEA in its recent Verification report, where it states, “During the reporting period, the Agency, based on the analysis of commercially available satellite imagery, observed additional damage to the former Karaj centrifuge manufacturing workshop.”

[16] IAEA Press Release, “Update on Developments in Iran,” June 19, 2025, .

[17] “Update on Developments in Iran,” June 19, 2025.