The newspaper, citing US officials, said Trump was weighing military action against the site after days of briefings from senior aides.
According to the Journal, Iran began building the underground complex near the Natanz nuclear facility in 2020 after an aboveground enrichment plant was damaged in what was widely seen as an act of sabotage. The following year, then-Iranian nuclear chief Ali Akbar Salehi said the site would house “sensitive” equipment.
The Journal, citing former US and Israeli officials, said the mountain complex could play an important role in any future Iranian effort to rebuild its nuclear program, although construction appears incomplete and it is unclear whether any nuclear activity is taking place there.
The report said Iran has not provided the International Atomic Energy Agency with design information for the site. IAEA Director General Rafael Grossi said in March that inspectors should be allowed to visit the facility.
The Washington-based Institute for Science and International Security estimated in a 2022 report that the underground complex could exceed 5,000 square meters (53,000 square feet) and could eventually house a uranium enrichment plant as well as other nuclear-related activities. The think tank also said recent satellite imagery showed construction had resumed after the June 2025 conflict.
The Journal quoted Dan Shapiro, a former senior Pentagon official in the Biden administration, as saying the site had become “a plausible target for attack” because Trump was concerned Iran could eventually reverse damage inflicted on its nuclear program during last year's war.
Matthew Sharp, a senior nuclear fellow at the Massachusetts Institute of Technology and former US diplomat to the IAEA, told the newspaper that Pickaxe is deeper underground and less well understood than Fordow, making it a more difficult target for airstrikes.