President Donald Trump continues to claim that the US will attack Iran’s Pickaxe Mountain – turning attention to the suspected underground nuclear site where Israel believes Tehran has stored part of its enriched uranium stockpile and advanced enrichment centrifuges.

“We’ll be hitting that area very probably pretty soon. And there’s not a thing they can do about it,” Trump said on Tuesday.

In response, Tehran warned that that any US attack on Iranian nuclear facilities would be treated as an expansion of the war in the region, state media reported early Wednesday.

Here’s what we know about Pickaxe Mountain.

Pickaxe Mountain is a heavily fortified facility located deep underground in the center of the country, about a mile south of the Natanz uranium-enrichment facility previously bombed by the US and Israel – making it a difficult target for the US and Israel, and for any potential ground operation.