A secret Iranian nuclear site buried deep inside a mountain must be “neutralized” before the end of the war, nuclear experts are warning the Trump administration.

Dubbed Pickaxe Mountain, the nuclear development facility is reportedly built about 100 meters beneath a granite mountain in northwest Iran. The site has never been visited by international nuclear inspectors, raising concerns about its purpose and capabilities.

According to experts, the facility’s depth and fortification could make it highly resistant to conventional airstrikes, potentially allowing Iran to continue nuclear development,s even amid the ongoing conflict.