WASHINGTON – The US can only determine with certainty that it has destroyed about a third of Iran’s vast missile arsenal as the US and Israeli war on the country nears its one-month mark, according to five people familiar with the US intelligence.

The status of around another third is less clear, but bombings likely damaged, destroyed or buried those missiles in underground tunnels and bunkers, four of the sources said. The sources spoke on condition of anonymity given the sensitive nature of the information.

One of the sources said the intelligence was similar for Iran’s drone capability, saying there was some degree of certainty about a third having been destroyed.

The assessment, which has not been previously reported, shows that while most of Iran’s missiles are either destroyed or inaccessible, Tehran still has a significant missile inventory and may be able to recover some buried or damaged missiles once fighting stops.

The intelligence stands in contrast to US President Donald Trump’s public remarks on March 26 that Iran had “very few rockets left”. He also appeared to acknowledge the threat from remaining Iranian missiles and drones to any future US operations to safeguard the economically vital Strait of Hormuz.

Reuters has reported that he is weighing whether to escalate the conflict by deploying US troops to Iranian shores along the Strait.

“The problem with the straits is this: let’s say we do a great job. We say we got 99 per cent (of their missiles). 1 per cent is unacceptable, because 1 per cent is a missile going into the hull of a ship that cost a billion dollars,” Mr Trump said at a televised Cabinet meeting on March 26.

The Pentagon and White House did not immediately respond to requests for comment.

Democratic Representative Seth Moulton, a Marine Corps veteran who served four tours in Iraq, declined to comment on Reuters’ findings, but he disputed Mr Trump’s claims about the impact of the war on Iran’s arsenal.