The United States 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 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 President Donald Trump’s public remarks on Thursday 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.

“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]. One per cent is unacceptable, because 1pc is a missile going into the hull of a ship that cost a billion dollars,” Trump said at a televised cabinet meeting on Thursday.

Asked for comment, a Pentagon official said Iranian missile and drone attacks were ​down by about 90pc since the start of the war. The US military’s Central Command “has also damaged or destroyed over 66pc of Iranian missile, drone, and naval production facilities and shipyards,” the official added.

The White House did not immediately respond to a ​request for comment.

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

“If Iran is smart they’ve retained some of their capability; they’re not using everything that they have. And they’re laying in wait,” Moulton said.

Iran’s missiles are prime US targets

The Trump administration has said it aims to weaken Iran’s military by sinking its navy, destroying its missile and drone capability and ensuring that the Islamic republic never has a nuclear weapon.

Central Command has ​said its operation, known officially as “Epic Fury”, is on schedule or even ahead of plans laid out prior to the February 28 start of the US and Israeli attacks on Iran.

US says its strikes have hit more than 10,000 Iranian military targets as of ​Wednesday and, according to Central Command, have sunk 92 percent of the Iranian navy’s large vessels. The US military has published imagery showing attacks on the factories that produce Iran’s weaponry and has stressed that it is not just pursuing missile and drone stockpiles, but ‌the industry that ⁠makes them.

Still, Central Command has declined to state precisely how much of Iran’s missile or drone capability has been destroyed.

One source said part of the problem is determining how many Iranian missiles were stockpiled in underground bunkers before the war started. The US has not disclosed its estimate of the size of Iran’s pre-war missile stockpile.

Israeli military officials say Iran had 2,500 ballistic missiles capable of reaching Israel before the war. Over 335 missile launchers have been “neutralised”, representing 70pc of Iran’s launch capacity, a senior Israeli military official claimed.

Israeli officials have not publicly disclosed how many actual missiles they believe Iran still possesses. They privately acknowledge that eliminating what they estimate to be the last 30pc of Iran’s capacity will be relatively more difficult to achieve.

Iran still firing at neighbours

Despite the heavy pace of US strikes, Iran ​has demonstrated that it has not run out of weapons.

On ⁠Thursday alone, it fired 15 ballistic missiles at the United Arab Emirates, along with 11 drones, according to the UAE’s Defence Ministry.

It has also displayed new capabilities. Last week Iranian forces for the first time fired long-range missiles, targeting the US-UK military base Diego Garcia in the Indian Ocean.

Nicole Grajewski, an expert on Iran’s missile forces and the Islamic Revolutionary Guard Corps at ​Paris’ Sciences Po university, said the Trump administration may have overstated how much US strikes have degraded Iranian capabilities.

She pointed to Iran being able to continue to carry out strikes ​from Bid Kaneh military facility, which ⁠has been heavily bombed.

“The fact that they’ve managed to sustain this, I think, indicates the US was overstating the success of its operation,” Grajewski said, adding she believed that Iran still retained about 30pc of its missile capabilities.

Grajewski said Iran had more than a dozen large underground facilities where it has been able to keep launchers and missiles, adding: “The big question is: have these facilities collapsed?”

Iran’s tunnelling

One senior US official voiced skepticism about the United States’ ability to accurately assess Iran’s missile capabilities, in part because it was unclear how many ⁠were underground and ​accessible in some way. “I don’t know if we’ll ever have an accurate number,” the official said.

Defence Secretary Pete Hegseth acknowledged the challenge posed by ​Iran’s tunneling in remarks on March 19, saying: “Iran is a vast country. And just like Hamas and their tunnels (in Gaza), they’ve poured any aid, any economic development, humanitarian aid, into tunnels and rockets.”

“But we are hunting them down methodically, ruthlessly and overwhelmingly, like no other military in the world can do, and ​the results speak for themselves,” he said, without providing details on the percentage of missiles or drones destroyed.