Renewed attention on Pickaxe Mountain keeps the tail risk of a significant escalation in play, since a strike on a site of this scale would go well beyond the tanker and infrastructure attacks that have driven oil higher in recent days. The site's granite construction and the acknowledgment that current US bunker busting weapons may not be capable of destroying it suggests any strike option is not imminent, which should limit near term market reaction. Still, the disclosure that the Pentagon is actively developing a next generation penetrator weapon, alongside a mysterious emergency test program, signals that a decisive move against the site remains on the table as a medium term possibility, which is likely to keep a geopolitical risk premium embedded in oil pricing. Separately, unverified online speculation has suggested the US could consider a tactical nuclear option against the site. This is not supported by CNN's reporting, which describes only conventional, non-nuclear weapons development, and should be treated as unconfirmed chatter rather than a credible scenario.---Reports on the potential for Trump's war to drag on and on for years will ignite more specualtion of harsher measures to come:Trump aides privately warn Iran war could last his full term, WSJ reports---Iran keeps digging deeper at its most fortified suspected nuclear site, and satellite evidence suggests the US is quietly working out how to reach it.Summary:CNN reports that satellite imagery analysed by the Center for Strategic and International Studies shows a clear surge in construction this year at Pickaxe Mountain, a suspected Iranian nuclear site near Natanz believed to be built to survive strikesCSIS analysts say the facility is likely intended as a centrifuge assembly site, an enrichment facility, or a safe haven for other nuclear weapons relevant work, and that recent activity has shifted toward internal construction and reinforcement of tunnel entrancesGranite construction makes the site a difficult target even for the Pentagon's heaviest current non-nuclear bombs, and CNN notes it is not the only Iranian nuclear facility believed to be out of reach of existing weaponsCNN has linked a February emergency contract for a "unique subterranean test facility" at White Sands Missile Range in New Mexico, awarded days before the war began, to US efforts to develop a way of targeting Iran's deepest bunkersTrump has repeatedly threatened to strike Pickaxe Mountain, and a source told CNN it was part of a target package under consideration this summer, though it remains unclear whether current US munitions could penetrate deep enough to destroy what Iran may have moved thereCSIS cautions that despite the construction, the site does not yet appear capable of enrichment work if that is its intended purposeA suspected Iranian nuclear site built deep beneath a granite mountain has seen a marked increase in construction activity this year, according to CNN, citing a satellite imagery analysis from the Center for Strategic and International Studies that has not previously been published. The site, known as Pickaxe Mountain, sits close to the Natanz nuclear complex south of Tehran and has long been viewed by intelligence agencies as a likely location for Iran to shelter its nuclear program from further strikes.CSIS analysts told CNN the facility is likely designed for one of three purposes tied to Iran's nuclear efforts: assembling centrifuges, enriching uranium, or serving as a broader safe haven for weapons relevant work such as uranium metal conversion. The report describes a shift this year from active excavation toward internal construction and reinforcement of tunnel entrances, along with paving of internal roads and increased vehicle activity at the site.The granite composition of the mountain makes it a difficult target for existing US weaponry, including the military's heaviest current non-nuclear bombs, and CNN notes it is not the only Iranian nuclear facility believed to sit beyond the reach of current-generation munitions. Even so, there are signs the Pentagon is working on new ways to strike such facilities. CNN links a February contract, signed days before the war with Iran began, for emergency repair work on a subterranean test facility at White Sands Missile Range in New Mexico to a broader effort tied to developing a next generation bunker penetrating weapon intended to succeed the current Massive Ordnance Penetrator. Satellite imagery reviewed by CNN shows excavation and testing related activity at the New Mexico site through February and March, though CNN could not independently confirm whether a test took place or its precise purpose.President Trump has repeatedly said the US could strike Pickaxe Mountain, and a source told CNN the site was included in a target package under consideration earlier this year. It remains unclear, according to that source, whether current US munitions could penetrate deeply enough to destroy whatever Iran may have relocated there. CSIS analysts caution that despite the extensive construction, the site does not yet appear capable of enrichment work, if that is ultimately its intended purpose, suggesting any decision on how or whether to strike it remains unresolved for now. This article was written by Eamonn Sheridan at investinglive.com.