The new PrSM munition is believed to have been used in a strike on an Iranian school, prompting concerns over potential design flaws

The American military depleted its entire stock of untested Precision Strike Missiles (PrSM) early in its attack on Iran last month, a US Army official has said.

The short-to-medium ballistic missiles developed by Lockheed Martin are slated to replace the aging Army Tactical Missile System (ATACMS). The new weapon completed its prototype phase only last year, and ended up being fielded without a full testing cycle. Media reports indicated that the new missiles were involved in at least one mass-casualty incident during the attack on Iran, killing some 21 people at a school and sports hall in the southern Iranian city of Lamerd.

A US Army unit equipped with the new missiles fully exhausted its inventory early in the conflict, Jimmy Arter, an official at Fort Sill, said. The official made the remarks at the Fires Symposium, which is underway at the Oklahoma Fires Innovation Science and Technology Accelerator (FISTA). 

"We shot our entire inventory of PrSM right now during the start of the war, and we've already got more coming in," Arter said, as quoted by Aviation Week. The attack on Iran has proven the new missile's capabilities and no further testing of PrSM is needed, Arter claimed.

A US Army spokesperson later said that a number of PrSM weapons remain in the military's inventory, Aviation Week noted. The Pentagon had ordered 130 before the 2024 fiscal year and a further 250 in 2025, yet it remains unclear how many munitions had been delivered.

The PrSM missile was likely used in the February 28 Lamerd strike, the New York Times reported early in the hostilities, citing visual evidence examined by weapons experts. The NYT said that, since the missile was new, it was difficult to assess whether the strike was "intentional" or stemmed from a design flaw of untested munition or faulty intelligence. 

The Pentagon denied its involvement, claiming it did not attack any targets in Lamerd on that day. The US Central Command pointed the finger at Tehran, claiming the munition visible in the footage of the attack was "consistent with the dimensions and silhouette of an Iranian Hoveyzeh cruise missile." The NYT, however, doubled down on its assessment last week, citing experts who said the munition lacked key features attributable to Hoveyzeh and looked like a PrSM.