Scholar Says Trump Disaster in Iran Helps Prove That Era of 'American Empire Is Over'

President Donald Trump's illegal war with Iran has gone so poorly that it portends the end of the American-led global order, foreign policy scholar Jennifer Kavanagh wrote in an analysis published Monday by The American Conservative.

Despite Trump's repeated declarations of a total US victory over Iran, Kavanagh wrote that the continued closure of the Strait of Hormuz has revealed the limits of the American military, which in 2025 had a budget of nearly $1 trillion.

Kavanagh, senior fellow and director of military analysis at Defense Priorities, argued that the Iran war has been particularly damaging to US power because it has drained US munitions supplies and has still achieved none of the major objectives Trump outlined at the start of the conflict.

"Some estimates suggest the United States has burned through 1,000 Tomahawk missiles, nearly 50% of its Patriot and THAAD stockpiles, and significant portions of advanced stand-off weapons like PRSM and JASSM missiles," Kavanagh wrote. "The constraints on US military power created by these shortages will be consequential and enduring."

In practical terms, Kavanagh said, this means the US simply cannot meet key commitments for the foreseeable future, such as supporting the defense of Taiwan in the case of an attack by China.

Kavanagh emphasized that American policymakers should reduce US military commitments around the world and not cling to a global order that is no longer sustainable.

"The period of US military dominance—and of American empire—is over," Kavanagh wrote. "The resulting future will be less comfortable for the United States, but its changes are overdue and its challenges manageable. With the right moves today, American retrenchment can leave the United States, and the world, better off."

This retrenchment, wrote Kavanagh, would refocus American defense strategy solely on defending US territory and "ensuring access to key economic markets." In practice, this would mean closing military bases and ending deployments in Europe and the Middle East, a "narrowing" of security guarantees to NATO allies, and explicitly stating that it would not defend Taiwan in the face of an attack from China, which Kavanagh said would "reduce the risk of a war with China that at this point the United States is unprepared to fight."

"These changes in posture and alliance commitments would amount to a massive transformation of American foreign policy," Kavanagh acknowledged, "but the result would be a sustainable military position, consistent with US capabilities and resources and tailored to protecting US interests."