‘Surge in construction’ at suspected Iranian nuclear site, analysts say, as US considers ways to strike deep underground

A suspected Iranian nuclear site buried under granite has seen a flurry of construction work this year as the war with the US has transpired, according to a group of analysts who reviewed six years of satellite imagery.

The Pickaxe Mountain site, located near the Natanz nuclear complex roughly 140 miles south of Tehran, has been the subject of steady discussion by intelligence agencies which view it as a likely location for Iran to protect future nuclear program efforts.

According to a new satellite imagery analysis by the Center for Strategic and International Studies think tank, shared exclusively with CNN ahead of its publication , there has been “a clear surge in construction activity” this year.

The underground facility is “likely” designed to be a safe haven for Iran’s nuclear program, according to the CSIS analysts.

Israeli intelligence has suggested that Iran may be seeking to move centrifuges to the location as part of uranium enrichment efforts, and President Donald Trump has repeatedly threatened to strike the site.

“We may hit Pickaxe very soon,” Trump told reporters last week, adding that “we know everybody that’s moving” at the site.

The granite mountain, however, presents a difficult target to even the Pentagon’s “heaviest non-nuclear” bombs, the CSIS team reported. And It’s not the only Iranian nuclear facility feared to be out of reach for current-generation weapons.

But there are signs the US is working to devise some means of striking those sites, even as US forces have largely focused on other types of targets during the six-month conflict with Iran.

Four days before the US launched Operation Epic Fury, a program manager at an obscure Pentagon agency charged with combating weapons of mass destruction signed an emergency $1.2 million contract justification to repair a “unique subterranean test facility at White Sands Missile Range” in New Mexico for a “live-fire test designed to validate classified capabilities against rapidly emerging threats.”

The document from the Defense Threat Reduction Agency was uploaded to a federal database on February 27 — the day before the war started.

The memo said the “rapid test prep,” as another database labeled the contract awarded to Pate Construction, needed to be complete within two-to-three weeks due to “a time-sensitive national security directive.”

The plans for the test were connected to the Iran war, three sources familiar with the matter told CNN, and the need to develop a way to target Iran’s deepest-buried underground facilities and, likely, simulate US strikes against specific nuclear facilities.

The US previously struck nuclear sites in June 2025 as part of what the military called Operation Midnight Hammer. While the strikes successfully destroyed some key locations linked to Tehran’s nuclear program, a top US general told lawmakers last year that the deeply buried Isfahan nuclear site only had its entrances buried because the Pentagon believed its bunker-busting bombs — known as the Massive Ordnance Penetrator — could not knock it out.

The military is working to develop a “next generation penetrator” bomb to succeed the current MOP and potentially hit targets even more deeply buried. A contract to begin work on a prototype was awarded in September 2025, and the Air Force solicited defense industry sources for the new weapon in June.

Satellite imagery reviewed by CNN shows that between February 16 and February 18, excavation work began at a remote DTRA and US Strategic Command-operated site at White Sands intended to test the effects of weapons on deeply buried targets. The timing aligns with that of the emergency contract: Pate Construction provided an estimate for the test work on February 17 and received the deal the next day, according to federal contracting records.

Work at the remote location, known as the Alternate Seismic Hardrock in Situ Test Site, continued into mid-March as a pile of excavation dirt gradually grew. The round of activity appeared to halt then, according to the imagery.

Similar to Pickaxe Mountain, the DTRA test site in White Sands is also carved into granite, according to an environmental assessment .

CNN could not independently verify whether the test occurred, nor could CNN confirm the purpose of the work at the DTRA test site observed via satellite imagery. The Pentagon did not immediately reply to questions from CNN. Pate Construction did not return calls from a CNN reporter.

The US military maintains operational plans for strikes against Pickaxe, and it was part of a target package that was under consideration earlier this summer when Trump was threatening to escalate the conflict with Iran, according to a source familiar with the matter. The strike plan for Pickaxe involved using some of the largest bombs in the US arsenal, though it remains unclear if those munitions can penetrate deep enough underground to destroy whatever Iran may have moved there, the source added.

Efforts to develop plans for decisive strikes against underground facilities continue; a source familiar with the matter told CNN that elements within the Defense Department recently held a “planning sprint” on the topic.

The facility at Pickaxe Mountain is “likely” designed for one of three purposes, all related to Iran’s nuclear program, according to the CSIS analysis. It could be a centrifuge assembly facility, an enrichment facility, or a safe haven for other “nuclear weapons-relevant” work such as uranium metal conversion.

In their report, the CSIS analysts argued the construction at the site “has shifted from active excavation toward probably internal construction and continued exterior reinforcement.” Pickaxe Mountain in 2026 has seen “more road activity” than ever before, and additional work has included “raising and hardening of the (tunnel) portal accesses, paving of the internal road network, reinforcement around access areas, and the flattening and removal” of dirt excavated while building its tunnels, the report said.

The CSIS analysts cautioned that the “continuous construction” they’ve observed at Pickaxe Mountain, among other factors, suggests the site “is not yet capable of enrichment work, if that is the intended purpose.”

CNN’s Tal Shalev contributed to this report.

Davis Winkie’s work at CNN is supported by a partnership between Outrider Foundation and Journalism Funding Partners (JFP). CNN retains full editorial control of the reporting.

据一组分析人士审查了六年来的卫星图像后发现，今年随着与美国的战争爆发，一个疑似伊朗核设施（埋在花岗岩下）的建设工程频繁进行。

位于德黑兰以南约 140 英里处、靠近纳坦兹核设施的皮卡克斯山遗址，一直是情报机构持续讨论的主题，他们认为这里很可能是伊朗保护未来核计划的地点。

根据战略与国际研究中心智库最新发布的卫星图像分析报告（该报告在正式发布前独家分享给了 CNN），今年“建筑活动明显激增”。

据战略与国际研究中心（CSIS）的分析人士称，该地下设施“很可能”是为伊朗核计划设计的安全避难所。

以色列情报部门表示，伊朗可能正试图将离心机转移到该地点，作为铀浓缩活动的一部分，而唐纳德·特朗普总统也多次威胁要打击该地点。

“我们可能很快就会在皮卡斯矿区开工，”特朗普上周告诉记者，并补充说“我们知道所有在矿区活动的人员”。

然而，据战略与国际研究中心（CSIS）团队报告，这座花岗岩山即使是五角大楼“最重的非核”炸弹也难以击中。而且，这并非唯一一个被认为超出当前一代武器打击范围的伊朗核设施。

但有迹象表明，美国正在努力想办法打击这些目标，尽管在与伊朗长达六个月的冲突中，美军主要将重点放在了其他类型的目标上。

在美国发起“史诗狂怒行动”前四天，五角大楼一个负责打击大规模杀伤性武器的鲜为人知的机构的项目经理签署了一份价值 120 万美元的紧急合同，用于修复新墨西哥州白沙导弹靶场的一个“独特的地下试验设施”，以便进行“实弹试验，旨在验证针对快速出现的威胁的机密能力”。

国防威胁降低局的这份文件于 2 月 27 日上传到联邦数据库——也就是战争爆发的前一天。

备忘录称，由于“一项有时效性的国家安全指令”，授予 Pate Construction 的合同（另一个数据库将其称为“快速测试准备”）需要在两到三周内完成。

三位知情人士告诉 CNN，此次试验计划与伊朗战争有关，目的是为了找到打击伊朗最深地下设施的方法，并可能模拟美国对特定核设施的打击。

美国此前曾在2025年6月对伊朗核设施发动了名为“午夜铁锤行动”的空袭。虽然空袭成功摧毁了与德黑兰核计划相关的一些关键地点，但一位美国高级将领去年告诉国会议员，深埋地下的伊斯法罕核设施之所以只掩埋了入口，是因为五角大楼认为其用于摧毁掩体的巨型穿透弹（MAPP）无法将其摧毁。

军方正在研发一种“下一代穿甲弹”，以取代现有的MOP炸弹，并有可能打击更深埋藏的目标。2025年9月，军方授予了一份启动原型弹研发工作的合同，空军于6月向国防工业界征集了这种新型武器的供应商。

CNN查阅的卫星图像显示，2月16日至18日期间，位于白沙导弹靶场一处偏远、由美国国防威胁降低局（DTRA）和美国战略司令部运营的场地开始进行挖掘作业，旨在测试武器对深埋目标的杀伤效果。这一时间与紧急合同的签订时间吻合：根据联邦合同记录，佩特建筑公司于2月17日提交了测试工作的报价，并在第二天获得了合同。

在这个被称为“替代地震硬岩原位试验场”的偏远地点，施工一直持续到三月中旬，挖掘出的泥土堆逐渐堆积起来。根据图像显示，这轮作业似乎随后停止了。

根据环境评估，与镐山类似，位于白沙的DTRA试验场也是在花岗岩上开凿出来的。

CNN无法独立核实此次测试是否发生，也无法确认通过卫星图像观察到的国防威胁降低局（DTRA）测试场地的工作目的。五角大楼尚未回复CNN的提问。Pate Construction公司也未回复CNN记者的电话。

据一位知情人士透露，美军制定了针对“镐头”地下设施的打击作战计划，该设施曾是今年夏天早些时候特朗普威胁要升级与伊朗冲突时考虑的目标之一。该消息人士补充说，打击“镐头”的计划涉及使用美国武库中一些威力最大的炸弹，但目前尚不清楚这些弹药能否穿透足够深的地下，摧毁伊朗可能在那里部署的任何目标。

制定对地下设施进行决定性打击的计划的努力仍在继续；一位熟悉此事的消息人士告诉 CNN，国防部内部一些部门最近就此议题举行了一次“计划冲刺”。

根据战略与国际研究中心（CSIS）的分析，皮克克斯山设施“很可能”是为以下三种用途之一而设计的，这三种用途都与伊朗的核计划有关。它可能是离心机组装设施、浓缩设施，或者其他“与核武器相关”工作的安全场所，例如铀金属转化。

在他们的报告中，战略与国际研究中心（CSIS）的分析师指出，该工地的建设“已从积极的挖掘工作转向内部施工和持续的外部加固”。报告称，到2026年，皮克克斯山（Pickaxe Mountain）的道路施工活动比以往任何时候都更加频繁，其他工作包括“抬高和加固（隧道）入口通道、铺设内部道路网络、加固通道周围区域，以及平整和清除”隧道施工过程中挖出的土方。

战略与国际研究中心 (CSIS) 的分析师警告说，他们观察到皮克克斯山“持续施工”等因素表明，该地点“目前还不具备进行浓缩作业的能力，如果这是其预期目的的话”。

CNN的塔尔·沙莱夫对本报道亦有贡献。

戴维斯·温基在CNN的工作得到了Outrider基金会和新闻资助伙伴（JFP）的合作支持。CNN对报道拥有完全的编辑控制权。