A new independent analysis from the Center for Strategic and International Studies (CSIS), a leading Washington-based think tank, has uncovered a stark strategic gap for the United States: it will take defense contractors a minimum of three years to fully rebuild stockpiles of three critical advanced weapons systems drawn down heavily by the ongoing Iran war. This timeline, the report warns, opens a multi-year window of vulnerability that could leave U.S. forces with constrained firepower if a high-stakes conflict erupts with China in the Indo-Pacific.
The three munition systems at the center of the assessment are long-range Tomahawk cruise missiles, which are designed to strike high-value targets deep inside hostile territory, and two top-tier air defense systems: Patriot interceptors and Terminal High Altitude Area Defense (THAAD) interceptors, which counter incoming enemy missiles and drones. In its report, shared exclusively with The Associated Press ahead of public release, CSIS emphasized that while the U.S. currently retains enough munitions to see through its ongoing operations in Iran, the drawn-down inventories have created direct risk for a potential confrontation in the Western Pacific. “The time needed to rebuild those inventories has thus become a major concern,” the report concluded.
Geopolitical tensions amplify this concern: China has outlined a public goal of building a military capable of seizing the self-governing island of Taiwan by force if deemed necessary by 2027, a timeline that defense experts widely view as an aspirational benchmark rather than a firm deadline. Just this month, however, Chinese President Xi Jinping issued a sharp public warning that missteps by Washington in its policy toward Taiwan could lead to open armed conflict between the two global powers.
The CSIS analysis accounts for the Trump administration’s proposed $1.5 trillion 2027 defense budget, a historic spending plan that has sharply accelerated the munitions production ramp-up that was first initiated under the prior Democratic Biden administration. While bipartisan support for expanding weapons stockpiles holds across Capitol Hill, the report stresses that the core constraint today is not funding — it is time. “It takes time to expand production capacity and to build these complex systems,” the report noted, adding that the vulnerability window will persist for several years until inventories return to pre-Iran war levels, and even longer to reach the force levels that U.S. war planners have identified as necessary for a major great power conflict. Though exact munitions stockpile numbers are classified, CSIS confirmed that sufficient unclassified data from public Pentagon budget documents allowed analysts to produce reliable, evidence-based production timeline estimates.
Top Trump administration officials have pushed back against claims of U.S. military unpreparedness. President Donald Trump and Defense Secretary Pete Hegseth have repeatedly insisted the U.S. is fully capable of winning any conflict it enters, and the administration has pressured defense contractors to accelerate production timelines. Testifying before lawmakers last month, Hegseth argued that the administration’s increased defense spending will enable manufacturers to double or even triple their current production capacity for advanced munitions. Chief Pentagon spokesman Sean Parnell reiterated this position in a formal statement, saying the U.S. military “has everything it needs to execute at the time and place of the President’s choosing.” He added that the U.S. has carried out multiple successful operations across global combatant commands while maintaining a deep arsenal of capabilities to protect American citizens and national interests.
Independent defense watchers and some military experts have challenged this optimistic framing. Virginia Burger, a senior defense policy analyst at the nonpartisan Project On Government Oversight watchdog and a former Marine officer, argued that Pentagon leaders have long been aware of the critical stockpile drawdown. “Pentagon officials 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,’” Burger said. Concerns over depleted munitions stocks have already been a central topic of discussion in recent congressional hearings, where lawmakers have clashed over the root causes of the gap. Congressional Democrats have framed the supply shortage as evidence of the reckless nature of the Iran war, which Trump launched without formal congressional approval. Some Republican lawmakers have attributed the gap to previous transfers of Patriot air defense systems to Ukraine following Russia’s 2022 full-scale invasion, though the interceptor system is used by a dozen and a half U.S. allies worldwide.
Mark Cancian, a retired Marine colonel and CSIS senior adviser who co-authored the report with research associate Chris H. Park, traced the current production bottleneck back decades to the end of the Cold War. After the collapse of the Soviet Union in 1991, Cancian explained, U.S. defense planners operated under the assumption that future conflicts would be short, regional engagements that did not require large stockpiles of advanced high-end weapons. As a result, the Pentagon placed consistently small orders for these systems, and defense contractors adjusted by maintaining a relatively small manufacturing footprint, rather than investing in expanded production capacity.
Russia’s protracted full-scale war in Ukraine upended that long-held assumption, proving that modern great power adjacent conflicts can drag on for years and require massive stockpiles of advanced precision weapons. At the same time, U.S. military strategists began running regular war games for potential conflicts in the Western Pacific, shifting planning priorities toward rebuilding large munitions inventories. “The thinking started to change, but it just takes time to build inventories,” Cancian said, noting that a core part of the delay is untangling and scaling up the complex network of specialized supply chains and subcontractors that produce the unique, high-precision components required for these advanced weapons systems. Cancian, who previously oversaw military hardware acquisitions at the Office of Management and Budget under both Republican George W. Bush and Democrat Barack Obama, added that the Biden administration deserves credit for initiating early outreach to the defense industry, allocating initial funding to expand the defense industrial base, and starting the production ramp-up. “A lot of people in the Trump administration are inclined to say that everything was terrible until they arrived, and that’s not true,” Cancian said. “Now, it is true that the Trump administration really increased funding.”
Breaking down specific replenishment timelines, CSIS estimates that the U.S. fired more than 1,000 Tomahawk cruise missiles during operations in Iran, and it will take until late 2030 to fully rebuild the pre-war stockpile. Currently, fewer than 200 Tomahawks are produced annually, a product of decades of small orders. Primary manufacturer Raytheon has set a target to ramp up production capacity to more than 1,000 missiles per year. RTX, Raytheon’s parent company, declined to comment directly on the CSIS findings because it had not received a full copy of the report, but confirmed it has committed several billion dollars in investments to expand production, including new and expanded facilities in Alabama and Arizona.
For THAAD interceptors, which were heavily used to shoot down Iranian missiles and drones, CSIS estimates it could take until the end of 2029 to replenish up to 290 deployed interceptors drawn down for the Iran war. Replenishment of more than 1,000 Patriot interceptors is projected to be completed by mid-2029. Lead contractor Lockheed Martin is currently ramping up production for both systems, and the report notes that THAAD delivery orders have been re-prioritized to meet U.S. domestic stockpile needs ahead of allied and partner requests. The report highlights a particular policy dilemma for Patriot interceptors: the U.S. must balance replenishing its own depleted stocks, continuing to supply Ukraine to fend off Russian missile attacks, and meeting existing delivery commitments to 17 other allied nations that operate the system. In a statement, Lockheed Martin said it is investing $9 billion in production expansion through 2030, and “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 vulnerability gap, the CSIS report notes that the outlook is not entirely negative. In recent years, the U.S. military has successfully demonstrated its advanced combat capabilities during operations against Iran, Venezuela, and Houthi rebel forces in Yemen. The report also argues that deterrence remains intact even during the replenishment window, noting that Chinese military leaders are deeply aware that the People’s Liberation Army has no recent large-scale combat experience, and performed poorly in its last major conflict — the 1979 border war with Vietnam. “That difference in experience may preserve deterrence until munitions inventories are restored,” the report concluded.
