Iran is using the ceasefire to dig up the missiles and other munitions stored underground or buried in US and Israeli strikes, a US official and two others familiar with the matter told NBC News.
According to NBC, the US believes that Iran is aiming to "quickly reconstitute" its capabilities to enable it to attack targets across the Middle East if fighting resumes.
One of the US officials added that US President Donald Trump is likely to decide on his next steps within the coming days.
Earlier this week, Trump admitted that Iran still has missiles and drones. US Secretary of State Marco Rubio told Fox News that Iran has "half the missiles" it had prior to the war, but "none of the factories."
Last month, US Secretary of War Pete Hegseth said in a Pentagon briefing that Iran, "can dig out for now, but you can’t reconstitute, but we can."
Asked by NBC for comment, a spokesperson for the Defense Department pointed to Hegseth’s remarks.