CNN, quoting a senior source in Tehran, has reported that the Islamic Republic will deliver a “devastating response” if Donald Trump carries out his threat to attack the underground facility known as “Kuh-e Kalang.” The warning comes as Pickaxe Mountain has emerged in recent years as one of Iran’s most critical and secure nuclear installations.

U.S. President Donald Trump announced in a media interview yesterday that Washington was closely monitoring a deep underground complex in Iran. He claimed that while there were currently no signs of overt activity at the site, the U.S. might soon deliver a “heavy blow” to the complex’s entrance tunnels.

Located in Isfahan Province, approximately 1.5 kilometres from the Natanz enrichment facility, Kuh-e Kalang Gazla, referred to in Western media as Pickaxe Mountain, is considered by experts to be one of Iran’s most resilient underground facilities because of its extreme depth and location beneath hard granite rock.

Technical estimates suggest that the complex’s underground halls have been excavated at depths ranging from 80 to 100 metres, reaching up to 600 metres in certain sections. This makes it even deeper than the Fordow enrichment site, leading some Western analysts to refer to the complex as Iran’s “nuclear fortress.”