More than five months into the United States’ war on Iran, concerns are growing over dwindling stocks of some of the military’s most effective weapons, despite President Donald Trump and his administration insisting that America’s arsenal remains well supplied.

Trump has repeatedly said the US has “massive amounts” of munitions after reports that the US had used up significant quantities of specific weapons while attacking Iranian targets and defending American bases and allies across the Middle East.

White House principal deputy press secretary Anna Kelly also said the US had “more than enough munitions, ammo, and stockpiles,” while defense companies were being urged to increase production. However, exact stockpile figures remain classified, making it difficult to determine precisely how many missiles are available to US forces.

Here are the five weapons systems the US is reportedly running low on:

1. Army Tactical Missile Systems (ATACMS)

The US Army has reportedly used up “virtually all” of its Army Tactical Missile Systems, according to Reuters. ATACMS are ground-launched ballistic missiles that allow US forces to strike targets hundreds of kilometers away with precision while keeping troops farther from the battlefield.

2. Precision Strike Missiles (PrSMs)

The Army has also reportedly used up “virtually all” of its Precision Strike Missiles. PrSMs are ground-launched ballistic missiles and are being phased in as the successor to ATACMS.

The missiles were first used in combat during the Iran war and have a publicly advertised range of more than 499 kilometers. A version capable of striking targets more than 1,000 kilometers away is also being developed.

3. Tomahawk Missiles

The US has reportedly used just under half of its Tomahawk stockpile since February, according to an unnamed source cited by Reuters.

The US fired more than 1,000 Tomahawks between the beginning of the war and late April, according to The Wall Street Journal, including more than 850 during the first month.

The ship-launched land-attack cruise missiles have been a staple of U.S. Navy operations since the 1980s.

4. THAAD Interceptors

The Terminal High Altitude Area Defense system has also come under significant pressure during the war.

The US had roughly 452 THAAD interceptors before the conflict, according to estimates from the Center for Strategic and International Studies. That number had fallen to as few as 234 by the end of July.

CNN reported Wednesday that the US had expended nearly 80 percent of its pre-war THAAD missile inventory. Reuters, citing two sources, reported that about two-fifths of THAAD missiles had been used.

5. Patriot Interceptors

Patriot air defense interceptors are another major concern. The systems are used to defend against incoming missiles, drones and aircraft and have been heavily sought after by countries including Ukraine.

CSIS estimated that the US had approximately 2,330 Patriot interceptors before the conflict. By July 27, the number had fallen as low as 759.

CNN reported that approximately half of the US pre-war Patriot interceptor inventory had been expended, while Reuters cited internal data showing about 65% had been used.

The reported shortages have raised concerns beyond the Iran war. Ukraine relies heavily on US air defense missiles, while analysts have warned that the US could face serious challenges in a potential conflict with China.