Restoring pre-war stockpiles of critical US munitions will take at least two years, according to CSIS report.

The United States has enough munitions for any plausible scenario in the Iran war, but rebuilding its depleted inventories will “take years”, according to a new report by the Center for Strategic and International Studies (CSIS).

Restoring pre-war stockpiles of four critical munitions heavily used by US forces during nearly 40 days of joint fighting with Israel against Iran would take at least two years – and in some cases more than three – the Washington-based think tank said on Wednesday.

While US officials publicly project confidence in weapons stockpiles, analysts have said that dwindling munition supplies may be shaping Washington’s calculations over whether to resume the war on Iran.

“Campaigns against Iran and its proxies – and, for Patriot interceptors, aid to Ukraine – have made the problem more acute,” said the CSIS report.

“Alongside replenishing its own stocks, the United States also has to fulfil orders from allies and partners.”

A finding by the think tank last month said that the four key munitions that had been depleted to more than half their pre-war inventory levels included the Land Attack Missile (TLAM), the Terminal High Altitude Area Defences (THAAD) interceptors, Patriot missiles, and the SM-3 and SM-6 ship-based surface-to-air missiles.

The Joint Air-to-Surface Standoff Missile (JASSM) and Precision Strike Missile (PrSM) will take several months to a year to replace, CSIS said. The pre-war PrSM inventory was low because the system had just begun production, while JASSM, though heavily used in the Iran war, will see large deliveries from recent procurements, it added.

“Decisions on how to allocate new production have already created bilateral friction, and this friction will continue for the next few years as demand outpaces supply,” the report warned.

The main problem is not funding but production time, limited manufacturing capacity and long procurement lead times, with CSIS noting that past procurement levels were relatively low for many systems, slowing replacement efforts despite recent increases in defence spending.

“There will be a window of vulnerability for several years until inventories return to their previous levels and another several years before they get to the levels that war planners desire,” said CSIS.

‘Strategic inventory shock’

US combat experience in recent conflicts may still help preserve deterrence against China during the replenishment period, it added.

Emerging evidence of depleting stockpiles of weapons has surfaced in recent weeks.

The Washington Post revealed earlier this month that the US used more of its advanced missile-defence interceptors to defend Israel than even Israel itself during the 40 days of the Iran war.

The US Navy last week paused $14bn in weapons sales to Taiwan that Congress has approved but President Donald Trump needs to sign off on. The navy’s secretary stating that it needs munitions for the Iran war.

Omar Ashour, a professor of security and military studies at the Doha Institute for Graduate Studies in Qatar, previously told Al Jazeera that while the Iran war did not empty the US arsenal of weapons, it burned through some of the most important and strategically valuable layers of it.

“It’s not tactical exhaustion, it’s just a strategic inventory shock if you wish, because that depletion will affect other theatres [of war],” Ashour said.

CSIS said last month that while the US has enough missiles to continue fighting the Iran war, the risk “which will persist for many years, lies in future wars”.