Iran Continues Work at Key Nuclear Site, Violating U.S.-Iran Agreement

New analysis of satellite imagery indicates that Iran is continuing construction at the deeply buried nuclear facility known as Pickaxe Mountain, in violation of the U.S.-Iran Memorandum of Understanding (MOU).

Since 2021, the Islamic Republic has maintained that Pickaxe Mountain is a centrifuge manufacturing facility. However, Western intelligence agencies suspect that Tehran is also building an undeclared uranium enrichment plant there.

The site is buried deeper than the Fordow enrichment plant, which was struck by the United States in June 2025, and could be impervious to airstrikes. Under the MOU signed on June 17, Tehran committed to “maintain the current status quo of its nuclear program.” Any reasonable reading of that commitment precludes further construction at nuclear facilities.

Iran’s continued activity raises questions about nuclear capabilities the regime may be advancing beyond the view of satellites. It also highlights that the MOU — already faltering because of continued Iranian provocations in the Strait of Hormuz — is unlikely to produce meaningful restrictions on Iran’s nuclear program.

New Activity Observed

The Institute for Science and International Security reported on July 2 that late-June imagery of Pickaxe Mountain showed “vehicle activity … on the roads leading to the open set of Western tunnel portals, indicating that construction inside the tunnel complex, as well [as] hardening of the tunnel entrance, are ongoing.” The Institute has previously documented Iranian efforts to fortify the site’s entrances against possible U.S. or Israeli strikes or raids, along with apparent construction inside the deeply buried tunnel complex.

Since the MOU was signed, the Institute has observed no significant activity at Iran’s other major nuclear sites — Fordow, Natanz, or Isfahan — all of which were targeted by the United States in June 2025. Washington did not strike Pickaxe Mountain at that time, likely because the facility was not yet nearing completion.

The regime has sharply limited International Atomic Energy Agency (IAEA) access to its nuclear sites since the June 2025 strikes, barring inspectors from legally required access to damaged facilities entirely. The IAEA has never visited Pickaxe Mountain under Iran’s comprehensive safeguards agreement, as Tehran has never declared it an enrichment facility. Since 2021, Iran has also suspended implementation of the Additional Protocol, which requires enhanced safeguards at centrifuge-manufacturing and other nuclear-related sites.

President Donald Trump has cited Iran’s resumed nuclear activity — ostensibly at Pickaxe — as one justification for new U.S. military strikes conducted between February and April 2026.

MOU Violation Must Be Explained, U.S. Military Preparations Warranted

Trump has repeatedly, and apparently successfully, warned Iran against attempts to recover surviving enriched uranium stocks for further enrichment to weapons-grade levels.

However, Tehran could, over time, still seek to resurrect its uranium fuel cycle at Pickaxe Mountain or elsewhere.

This might include deploying a surviving set of a few hundred advanced centrifuges to Pickaxe for enrichment, along with potential new weaponization efforts. To advance this option, Iran would prioritize completion of the Pickaxe facility, advancing the work under the cover of negotiations with the United States while continuing to benefit from sanctions relief to stabilize its economy.

The United States must demand that Iran explain the observed activity and its clear violation of the MOU. To test Tehran’s seriousness about negotiations and its interpretation of the agreement, Washington should insist that Iran grant IAEA inspectors immediate access to the site to determine the true nature of its work.

If Iran stonewalls or continues construction, the United States must prepare credible military options to disable Pickaxe or render it inaccessible or inoperable.

Andrea Stricker is a research fellow and deputy director of the Nonproliferation Program at the Foundation for Defense of Democracies (FDD). For more analysis from the author and FDD, please subscribe HERE. Follow Andrea on X @StrickerNonpro. Follow FDD on X @FDD. FDD is a Washington, DC-based, nonpartisan research institute focused on national security and foreign policy.