US faces years-long gap in rebuilding key weapons stockpiles after Iran campaign, think tank warns
WASHINGTON (AP) — Rebuilding the U.S. military’s depleted inventories of three cornerstone weapons systems used extensively during the Iran war will take at least three years and possibly stretch into the next decade, according to a report published Wednesday by the Center for Strategic and International Studies (CSIS). The findings underscore growing anxiety among defense analysts over America’s ability to sustain a major conflict — particularly one with China — while its stockpiles remain below prewar levels.
The weapons in question — Tomahawk cruise missiles, Patriot interceptors and Terminal High Altitude Area Defense (THAAD) systems — were heavily relied upon in operations against Iran. The report, shared with The Associated Press, warns that even with historic defense spending proposed by the Trump administration, time, not money, is the critical bottleneck.
“The United States has enough munitions for any plausible scenario in the Iran war, but the depleted inventories have created a window of vulnerability for a potential Western Pacific conflict,” the report states. “The time needed to rebuild those inventories has thus become a major concern.”
China has long signaled its intent to be capable of taking Taiwan by force, with officials often referencing 2027 as an aspirational target. While many experts view that date as more of a guideline than a firm deadline, Chinese President Xi Jinping recently warned that mishandling ties with the self-governing island could lead to confrontation or open conflict with Washington.
The CSIS analysis incorporates the Trump administration’s proposed $1.5 trillion defense budget for fiscal 2027 — a record figure that boosts spending on high-end munitions, building on efforts begun under President Joe Biden. But the report concludes that production capacity cannot be scaled up overnight.
“It takes time to expand production capacity and to build these complex systems,” the report notes, adding that the vulnerability gap will persist “for several years until inventories return to their previous levels and another several years before they get to the levels that war planners desire.”
President Donald Trump and Defense Secretary Pete Hegseth have repeatedly asserted that the U.S. military remains fully capable of fighting any adversary. Hegseth told lawmakers last month that the administration is pushing contractors to double or even triple their output. Chief Pentagon spokesman Sean Parnell echoed that message, saying in a statement that the military “has everything it needs to execute at the time and place of the President’s choosing.”
But some military experts question whether those assurances match reality. Virginia Burger, a senior defense policy analyst at the Project On Government Oversight and a former Marine officer, said Pentagon officials likely knew the risks before launching the Iran campaign. “They knew the reality of our military stockpiles and hopefully told someone, ‘Hey, if we go to this fight, even in the most conservative estimates, we are drawing down our stockpiles to a critical level,’” she said.
On Capitol Hill, the issue has become a flashpoint. Democrats point to the depleted inventories as evidence that Trump launched military action without congressional approval, while some Republicans blame the earlier decision to send Patriot systems to Ukraine after Russia’s 2022 invasion. The report notes that Patriot deliveries now face a three-way squeeze: restocking U.S. supplies, helping Ukraine defend against Russian missiles, and meeting commitments to 17 other allied nations that operate the system.
Mark Cancian, a retired Marine colonel and senior adviser at CSIS who co-authored the study with research associate Chris H. Park, traces the roots of the problem to the end of the Cold War. After the Soviet Union collapsed, he said, the U.S. assumed future wars would be short and regional, requiring relatively few high-end weapons. The Pentagon ordered in small quantities, and contractors built accordingly.
Russia’s war in Ukraine shattered that assumption, showing that modern conflicts can be protracted and demand deep reserves of advanced munitions. At the same time, U.S. war games in the western Pacific revealed potential shortfalls. “The thinking started to change, but it just takes time to build inventories,” Cancian said, emphasizing the challenge of reviving a complex web of supply chains and subcontractors that produce specialized components.
Cancian credited the Biden administration for initiating conversations with the defense industry, investing in the industrial base and ramping up production. “A lot of people in the Trump administration are inclined to say that everything was terrible until they arrived, and that’s not true,” he said. “Now, it is true that the Trump administration really increased funding.”
The numbers are stark. According to CSIS estimates, the U.S. fired more than 1,000 Tomahawk cruise missiles at Iran, and at current production rates — fewer than 200 per year due to historically small orders — replenishing the prewar inventory could take until late 2030. Manufacturer Raytheon has set a goal of boosting capacity to more than 1,000 annually, but that ramp-up will take years.
For air defense systems, the picture is similar. Replacing as many as 290 THAAD interceptors could take until the end of 2029, while replenishing more than 1,000 Patriot interceptors is expected to wrap up in mid-2029. Lockheed Martin, which produces both systems, has announced a $9 billion investment through 2030, including a new facility in Alabama. However, CSIS noted that deliveries of THAADs “were apparently re-sequenced to prioritize U.S. needs over those of allies and partners.”
Lockheed Martin said in a statement that it “is already delivering tangible results to meet heightened munitions demand, including a new facility in Alabama announced last week along with more than 20 others across the United States.”
Despite the grim timeline, the report points to one factor that could buy time: recent combat experience. The U.S. military has demonstrated its capabilities in operations against Iran, Venezuela and Houthi rebels in Yemen. “China is deeply aware that it has no recent combat experience and that it performed poorly in its last war — against Vietnam in 1979,” the report says. “That difference in experience may preserve deterrence until munitions inventories are restored.”