As the US restarts war on Iran, is its weapons stockpile running low?

United States President Donald Trump is scheduled to address a defence summit at the US Army War College on Wednesday, where he is expected to laud US investments in its armed forces that he has argued have helped add a new edge to history’s most powerful military.

But his speech comes at a time when the US’s war on Iran has significantly depleted the US military’s weapons stockpile.

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The summit, which will be held in Carlisle, Pennsylvania, comes as the US has re-ignited attacks on Iran in the past week, and as Trump has threatened to continue a war that, according to recent US polls, is highly unpopular among Americans facing high costs of living.

The US has expended half of at least four of its most critical munitions since its war on Iran began on February 28, and has racked up billions of dollars in weapons expenses, analysis shows.

Replenishing low stockpiles could take anywhere between several months and several years. Analysts warn that a shrinking arsenal could put the US in a less formidable position in a potential future conflict – particularly against China.

Here’s what we know about the US weapons inventory:

A projectile approaches a target at an unknown location, during what US Central Command (CENTCOM) says are strikes on Iran, in this screengrab taken from a handout video released on July 12, 2026 [US Central Command/Handout via Reuters]

What’s happening with the US-Iran war?

Following an April ceasefire between the US and Iran, and the subsequent signing of a memorandum of understanding in June, the conflict kicked off again after the US Central Command launched heavy waves of attacks on Iran’s military sites last Wednesday, saying it was aiming to degrade Tehran’s military capabilities. Huge, hourlong attacks have continued for four nights since Sunday, including on railway tracks and bridges.

Both sides traded low-intensity attacks throughout the ceasefire period. However, the US escalated air attacks last week after Iran fired on three commercial ships passing through the Strait of Hormuz – because those vessels had used a shipping route not approved by Tehran.

Each blames the other for violating the ceasefire, and at last week’s NATO leaders’ summit, Trump declared the pact with Iran over, although he said American negotiators could continue talks. Washington has also reinstated a naval blockade on Iran-linked ships trying to transit the waterway and has re-imposed sanctions on Iran.

Iran’s Islamic Revolutionary Guard Corps has responded with retaliatory attacks on US military assets in Bahrain, Oman, Qatar and Kuwait.

More than a dozen people have been killed in Iran since the new wave of US attacks, including civilians.

“We’re going to knock out all their power plants. We’re going to knock out all their bridges unless they get to the table and negotiate,” Trump threatened in a Fox News interview that aired on Tuesday.

Attacking civilian infrastructure is a violation of international law.

Smoke rises from an explosion following a drone attack on a warehouse in al-Shuaiba, Kuwait, in this still image obtained from social media video released on July 14, 2026 [Social media via Reuters]

Does the US have enough weapons to keep attacking Iran?

Washington’s supplies are running low but have not reached a critical level, according to analysis of the US weapons inventory by the Center for Strategic and International Studies (CSIS), a Washington-based think tank.

In the 39 days of conflict between the start of the US-Iran war in February and the ceasefire in April, the US hit more than 13,000 targets, focusing mainly on using seven of its most powerful missiles and air defence systems: Tomahawk missiles, Joint Air-to-Surface Standoff Missiles (JASSM), Precision Strike Missiles (PrSM), Standard Missile-3 (SM-3), Standard Missile-6 (SM-6), Terminal High Altitude Area Defenses (THAAD) and Patriots.

For at least four of the munitions, Washington likely expended more than half of its available stockpiles, although many lower-grade alternatives are still in stock, according to CSIS. Government data on weapons inventory is classified.

Here’s how the munitions were used:

• Tomahawks – The US had about 3,000 of the long-range missiles that are fired from sea at ground targets. It likely used up more than 1,000 in the war on Iran.
• JASSM – About 4,000 of these stealthy, air-launched long-range missiles were in the US inventory before the war. About 1,100 were used in the war on Iran.
• PrSM – Supplies of the newly delivered, ground-launched long-range missiles were already low to start with, with deliveries since 2023 amounting to a total of 90. An estimated 40-70 were used in the war. One US military official claimed that the “entire” inventory had been expended.
• SM- 3 – The most expensive weapon per unit at $28m, these ship-launched ballistic missile interceptors numbered about 410 before the war. The US has used between 130 and 250 of these in the war on Iran.
• SM-6 – Also ship-launched, this missile is mainly used to intercept aircraft and cruise missiles. The US had about 1,160 stockpiled. An estimated 190- 370 have been expended in the Iran war.
• THAAD – The US had about 360 of the costly anti-ballistic missile systems by April, and between 190 and 290 were used in the war. The US has a total of 8 THAAD units or “batteries” consisting of launchers, interceptors, and radar systems.
• Patriot – An estimated 2,330 Patriots were in stock before the war, but between 1,060 and 1,430 have been expended. Some older versions may also likely be available – about 400 of them.

What does this mean?

Analysts from CSIS say that while the US may have enough to continue hitting Iran in the near-term war, it has reduced its stockpiles so significantly that it may not have enough for potential future wars, especially against a formidable rival like China.

Replenishing high-capability and costly weapons like the ones the US has used in Iran will likely take several years.

Trump and senior administration officials have publicly maintained that the US has an “unlimited” supply of weapons as the US-Iran war has raged on.

However, in March, Trump said administration officials met with the heads of US manufacturers, including Lockheed Martin, Boeing, Raytheon, BAE Systems, Honeywell Aerospace, L3Harris Missile Solutions, and Northrop Grumman. He said all promised to “quadruple” production and that increased manufacturing was already under way.

Subsequently, in June, Trump signed the Defense Production Act, an executive order compelling US weapons manufacturers to speed up production, citing existing conditions “which may pose a direct threat to the national defense or its preparedness programs”.

An order compelling private actors to ramp up production likely reflects timeline concerns within the Pentagon, analysts note.

In the short term, Washington is also unlikely to meet demands from its allies, and may not have the capacity to supply the THAADs and Patriots that Ukraine says are crucial in its war against Russia.

Already, supply orders have hit road bumps. Japan’s order of 400 Tomahawks from Raytheon was meant to be delivered between 2025 and 2027, but US Defense Secretary Pete Hegseth said in May that two more years could be added to the schedule.

Meanwhile, Switzerland began negotiations with France, Israel and South Korea in June to buy another missile defence system after its 2022 order from Lockheed Martin and Raytheon continued to face delays.

How long will replenishing weapons take?

Hegseth said in May that it could take “months and years” to replenish the supplies, based on the weapons system.

Analysts reckon it could take the US between one and four years to get its most exquisite munitions stockpiles back to pre-Iran war levels, even as Trump has boasted that new weapons plants are being built around the US and production is being ramped up.

Trump’s administration is set to buy large amounts of advanced munitions in its proposed $1.5 trillion 2027 defence budget – a 44 percent increase from 2026’s defence budget.

According to CSIS, estimated timelines to replenish the seven critical munitions, based on existing production facilities, are:

• Tomahawk: Between 4- 5 years (207 will be delivered in 2026, while 785 have been requested for 2027).
• JASSM: 1 year (821 to be delivered in 2026 and 821 requested for 2027).
• PrSM:  8 months (70 to be delivered in 2026 and 1,134 requested for 2027).
• SM- 3:  3 years ( 52 to be delivered in 2026 and 214 requested for 2027).
• SM-6:  3 years (125 to be delivered in 2026, and 540 requested for 2027).
• THAAD: 3 to 3.5 years (92 to be delivered in 2026, and 857 requested for 2027).
• Patriot: 3 years (172 to be delivered in 2026, and 3202 requested for 2027).