Speaking to reporters at the Oval Office on Friday, US President Donald Trump issued a fresh warning about Iran's nuclear program. He said the United States could "hit" a heavily fortified underground nuclear site "very soon" if activity is detected there.

Trump referred to the site as "Pickaxe Mountain" and said US intelligence is closely monitoring who is moving at that site and across Iran. "We know everybody that's moving at Pickaxe; we know everybody that's moving everywhere all over Iran. And if anything goes bad, we hit them; we hit them hard," he said.

Trump also defended the US military campaign in Iran, saying its primary objective is to prevent Tehran from acquiring a nuclear weapon.