US diverts JASSM-ER missiles to Iran, risking deterrence vs China

The US decision to shift its most advanced long-range cruise missiles to the Iran war is exposing a growing strain on its global strike posture as high-end munitions are pulled from other theaters.

The US is committing nearly its entire stock of stealthy long-range JASSM-ER cruise missiles to the Iran war, drawing heavily from reserves previously allocated to other regions, including the Pacific, The South China Morning Post reported citing anonymous sources familiar with the matter.

The decision, reportedly issued in late March, will see the missiles redeployed to US Central Command (CENTCOM) bases and Europe as the US intensifies its air campaign launched with Israel on February 28.

Capable of striking targets from over 965 kilometers with a 450-kilogram warhead designed for hardened and soft targets while evading air defenses, the JASSM-ER has been used extensively in the first four weeks of fighting in Iran. About two-thirds of US JASSM inventories are now reportedly committed to the conflict.

Only about 425 usable missiles remain globally from a pre-war stockpile of 2,300, raising concerns about reduced readiness against higher-end adversaries such as China. The campaign has relied heavily on standoff weapons to minimize risk to personnel, though recent US losses, including downed aircraft and drones, highlight ongoing threats.

Given current production rates, replenishment of JASSM-ER stocks is expected to take years, even as the US Department of Defense (DoD) expands manufacturing capacity.

The escalation comes amid uncertainty over next steps in the Iran war, with US President Donald Trump signaling further intensification of operations. That operational demand is now driving a rapid and potentially unsustainable rate of munition expenditure.

At the same time, the reallocation of JASSM-ER stocks, a standoff weapon designed to penetrate defended airspace, could imply that Iran’s air defenses remain a substantial threat, despite American claims to the contrary.

In March 2026, the Wall Street Journal reported that 85% of Iran’s air defense systems and radars have been neutralized, with 100 anti-aircraft batteries and 120 radars destroyed, citing Israeli military sources.  

However, the New York Times reported this month that multiple shoot-downs of US aircraft, specifically those of an F-15E and an A-10, are proof that, despite being substantially degraded, Iran’s air defenses are still a threat to US operations.

Citing US intelligence reports, the NYT notes that Iran has maintained much of its capabilities underground, which could have saved some systems from US and Israeli airstrikes, and that even if underground bunkers and silos could appear to be damaged, Iran has been able to dig out the launchers and fire them again quickly.

Despite these operational demands, the cost of sustaining such air strikes is becoming increasingly evident. More than five weeks into the Iran war, the US may be staring down a shortage of long-range standoff munitions, forcing a reliance on less-capable alternatives.

In a March 2026 press briefing, the Chairman of the Joint Chiefs of Staff, General Dan Caine, stated that the use of such munitions — specifically the Tomahawk cruise missile — may need to be replaced with less sophisticated munitions such as Joint Direct Attack Munitions (JDAM) and AGM-114 Hellfire missiles.

Both have significantly shorter ranges than the JASSM-ER. Highlighting the possible JASSM-ER expenditure rates during intensified air strikes against Iran, Macdonald Amoah and other authors mention in a March 2026 Foreign Policy Research Institute (FPRI) article, citing data from the Payne Institute, that in the first 96 hours of Operation Epic Fury, the US launched 135 JASSM/JASSM-ER missiles. That rate could exponentially increase should the US opt to intensify operations over Iran, as Trump has threatened.

In their analysis, Amoah and others note that the pace of operations is consuming munitions faster than they can be replenished, particularly long-range strike systems such as the JASSM-ER. They highlight a gap in US industrial resilience, particularly in sourcing minerals and materials essential for manufacturing more munitions and weapon systems.

This imbalance between consumption and replenishment reflects deeper structural constraints. Seth Jones’s January 2023 Center for Strategic and International Studies report highlights gaps in US military resilience, noting that the defense industrial base operates at a peacetime pace with limited surge capacity, risking rapid depletion of stockpiles during major conflicts.

He emphasizes the industry’s risk-averse nature, reliance on multi-year contracts and 12–24-month lead times for critical components, which delay output. Jones also criticizes outdated acquisition regulations and sluggish funding processes that hinder responsiveness, as well as wartime logistical challenges that complicate replenishment and distribution.

Reinforcing this point, Tyler Hacker’s June 2023 Center for Strategic and Budgetary Assessment report underscores fiscal constraints on munitions such as JASSM-ER, with procurement accounting for only a small share of defense spending, thereby limiting production despite rising demand.

Hacker notes the defense industry is optimized for efficiency, not scale, with complex, high-end designs increasing production time and cost. He highlights that reliance on advanced components and technology makes rapid-surge capability impossible for sophisticated munitions, thereby rendering existing inventories the key to near-term warfighting capacity.

Taken together, these burn rates and institutional constraints could mean the US effectively disarms itself in the Pacific to sustain operations in Iran. Noting the potential depletion of munitions in a possible conflict with China over Taiwan, a CSIS briefing shows that starting with a stockpile of 500 JASSM-ER missiles, these supplies would be exhausted 30 days into a four-week operation.

In this context, if Chinese leaders intend to carry out their longstanding threat to invade Taiwan, the optimal window for action could be within the next three or four years, when the missile gap with the US will be at its widest.

If current burn rates persist, the US risks degrading its high-end strike capacity in the Indo-Pacific, potentially undermining conventional deterrence against China and protection of regional allies at a time when replenishment timelines lag behind operational demand.