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10/27/2025 | Press release | Distributed by Public on 10/27/2025 09:51
CSIS Satellite Imagery Analysis Reveals Possible Signs of Renewed Nuclear Activity in Iran
CSIS Satellite Imagery Analysis Reveals Possible Signs of Renewed Nuclear Activity in Iran
Photo: Satellite image (c) 2025 Maxar Technologies/Getty Images
Commentary by Joseph Rodgers and Joseph S. Bermudez Jr.
Published October 27, 2025
On October 18, Iran's Ministry of Foreign Affairs officially announced that all of its obligations under the 10-year-old Joint Comprehensive Plan of Action-the Iran deal-have expired. This declaration formally ends all international oversight of Iran's nuclear program. Since the June attacks on Iran's nuclear program by the United States and Israel, Iran has pushed its nuclear program into a new era. Iran's program is increasingly defined by strategic opacity, operational chaos, and a likely internal culture of fear. New satellite imagery points to emerging risks from Iran's nuclear program despite the damage from the U.S. and Israeli strikes.
Days before the U.S. and Israeli strikes on Iran's nuclear program, International Atomic Energy Agency Director General Rafael Grossi stated that Iran was constructing a third enrichment site near Isfahan. There is an underground tunnel just to the north of Isfahan, which is likely the site of the new enrichment facility. Compounding these concerns, on June 24, U.S. Vice President JD Vance suggested that Iran likely still has possession of its existing stockpile of 400 kilograms (kg) of highly enriched uranium (HEU) enriched to 60 percent. Future Iranian efforts to build a nuclear weapon would likely require a new enrichment site capable of producing 90 percent enriched uranium, expanded centrifuge-assembly capacity, and metallurgy facilities to produce uranium hexafluoride (UF₆) for enrichment.
The Aftermath of the Strikes
Operation Midnight Hammer and Operation Rising Lion destroyed key areas of Iran's nuclear program. The United States struck three key nuclear facilities on June 22 at Fordow, Natanz, and Isfahan. Before the strikes, Iran was enriching uranium at Fordow and Natanz and processing uranium metal at Isfahan. Satellite imagery of each of the three facilities reveals virtually zero activity or attempts to rehabilitate these sites. Transformers and power generators were destroyed during the strikes against Natanz, and these essential pieces of site infrastructure have not been reestablished. At Isfahan, debris remains visibly scattered in the roadway, blocking access to many of the damaged buildings. Based on these images, it is clear that the U.S. strikes effectively halted uranium enrichment and uranium processing at these critical sites.
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Joseph Rodgers
Deputy Director and Fellow, Project on Nuclear Issues
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Joseph S. Bermudez Jr.
Senior Fellow for Imagery Analysis, iDeas Lab and Korea Chair
Programs & Projects
- Project on Nuclear Issues
- Defense and Security
- Geopolitics and Foreign Policy
Remote Visualization
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Remote Visualization
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While direct progress on the most sensitive aspects of Iran's nuclear program has been minimal, Iran has continued construction at Pickaxe Mountain, a deeply buried facility just one mile south of the Natanz uranium enrichment site. In July of 2020, a fire broke out at a centrifuge assembly hall at Natanz, likely due to sabotage. After that, the head of Iran's nuclear program, Ali Akbar Salehi, stated that Iran would build a more modern and larger centrifuge assembly hall "in the heart of the mountain near Natanz." Construction of that facility, buried in Pickaxe Mountain, began in 2020.
Since the U.S. strikes in June, Iran has stepped up construction at the Pickaxe Mountain site. By comparing images from June 30 and September 30, CSIS analysis determined that Iran has constructed a security wall around the entire perimeter of the site. There are tunnels to the west, east, and south of the site. There are visible signs of construction at the site. At the eastern end of the site, the underground facility consists of two portals. The northern of these two portals has recently been extended and is being covered by gravel and sand. The western area also consists of two portals, both of which are open in the imagery. The western of these two portals has also recently been extended and is being covered by gravel and sand. The southern area consists of a single portal. A dirt beam is placed in front of this portal, which suggests that the southern portal is not actively being used.
While it is difficult to definitively assess the full purpose of Pickaxe Mountain from imagery alone, the construction of a large underground facility just one mile south of Natanz is highly suspicious and has sparked considerable speculation. When asked about construction activities at Pickaxe Mountain on September 26, Iranian President Masoud Pezeshkian said that satellite imagery was insufficient to determine what was happening at the site and called for International Atomic Energy Agency (IAEA) inspectors on the ground to verify the site's purpose. Unfortunately, Tehran is demanding transparency while simultaneously banning the very inspectors who could provide it.
Remote Visualization
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Remote Visualization
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There are at least three potential explanations for this activity at Pickaxe Mountain. First, Iran may be pushing to construct the centrifuge assembly facility as initially planned. Given the uptick in pace, the timeline for Pickaxe Mountain's operation has likely moved up. Second, Iran could be expanding the scope of the mission at Pickaxe Mountain, pushing activities like metallurgy, which was destroyed in Isfahan, into the Pickaxe Mountain facility. Third, Iran may be pursuing a clandestine uranium enrichment facility at Pickaxe Mountain, with the hopes that this facility could enrich Iran's existing stockpile of 400 kg of 60 percent enriched uranium. Regardless of the true explanation, the main takeaway is that this increased activity points to the renewed need for greater transparency into Iran's nuclear activities and ambitions, which only the IAEA and international diplomacy can provide. It's worth noting that Iran has many other UGFs around the country. Iran could also covertly move many of the aspects of its nuclear program to these other facilities.
The Importance of Tacit Knowledge
In addition to destroying Iran's key nuclear facilities, Israel's military operation took out key scientific leadership in the Iranian nuclear program. Israeli Ambassador Joshua Zarka told reporters that Israeli strikes in June killed at least 14 leading nuclear scientists, including 9 who were targeted in Israel's initial strikes on June 13. These scientists had knowledge of chemistry, engineering, and nuclear physics and were involved in dual-use research that has the potential for weaponization. The technical expertise held by these highly skilled workers is difficult to replace, often requiring years of dedicated training. Consequently, the loss of scientific and technical leaders will severely impair Iran's ability to attract and maintain the vital tacit knowledge necessary for sustaining and advancing a future nuclear weapons program.
The scope, precision, and breadth of the U.S. and Israeli military strikes indicate that U.S. and Israeli intelligence assets deeply penetrated Iran's nuclear and military programs. In the years leading up to the June 2025 strikes, Iran's nuclear program suffered repeated targeted losses, including sabotage and assassinations. While these efforts have set back Iran's program, Iran has historically found a way to rebuild facilities and recruit new scientists. More recent security failures have led Tehran to launch a fierce internal crackdown, focusing on counterintelligence efforts. On June 25, Iranian intelligence forces arrested over 700 Iranians accused of spying for Israel. To further emphasize their hardline approach, Iran executed two men in September who were accused of meeting with Mossad, Israel's spy agency. More broadly, Iranian hardliners have taken more draconian measures in 2025. The Norway-based nonprofit Iran Human Rights claims that Iran has executed at least 1,000 people in 2025, which is more than at any time in the past three decades.
This mass arrest and execution campaign is likely creating a culture of fear in the Iranian nuclear and military organizations. If Iran wants to resume its nuclear operations, it will need to figure out how deeply Mossad penetrated its program. When and if the nuclear program resumes full-scale operations, it will likely suffer from pervasive distrust. In the aftermath of the 12-day war, Iran is rethinking the security arrangements that guard its nuclear scientists. An Iranian official reportedly told The Telegraph that several surviving nuclear scientists don't trust their own bodyguards and have requested replacements. A renewed emphasis on security and secrecy could significantly impact the productivity and pace of a future dash to rebuild nuclear capacity. Repairing damaged facilities is difficult, but rebuilding trust and human capital are equally challenging problems.
Policy Implications and the Future of Iran's Nuclear Activities
The termination of the Iran deal and Iran's expulsion of international inspectors are troubling signs for the future of Iran's nuclear program. Iran likely possesses a stockpile of 400 kg of 60 percent enriched HEU, and it is unclear how quickly Iran can begin enrichment at its third enrichment facility at Isfahan. Despite this, there are technical and social challenges that will impede attempts by Iran to dash toward a bomb.
Going forward, Iran's approach to the nuclear Non-Proliferation Treaty (NPT) and its upcoming 2026 Review Conference will be a key indicator of how Iran is posturing. Iran's Deputy Foreign Minister Kazem Gharibabadi has threatened that Iran could withdraw from the NPT, which is widely regarded as the cornerstone treaty to prevent the spread of nuclear weapons. North Korea is the only country to have previously withdrawn from the NPT, and after it did so, it continued developing a clandestine nuclear weapons program. Under the NPT, Iran is obligated to allow IAEA inspectors to monitor its nuclear facilities under comprehensive safeguards.
If Tehran continues to deny international access to its nuclear program while actively constructing secretive underground facilities such as Pickaxe Mountain, Iran could build back key aspects of its nuclear program in the dark. The international community must pressure Iran to comply with the NPT and cooperate with the IAEA as a prerequisite for any meaningful future dialogue.
Joseph Rodgers is deputy director and fellow with the Project on Nuclear Issues in the Defense and Security Department at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Joseph S. Bermudez Jr. is a senior fellow for imagery analysis with the iDeas Lab and Korea Chair at CSIS.
Commentary is produced by the Center for Strategic and International Studies (CSIS), a private, tax-exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).
© 2025 by the Center for Strategic and International Studies. All rights reserved.
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