The evolution of the US defense budget reflects the continued rise of the United States and the transformation of war into a sustainable mode of organization for the federal government. Before 1914, military spending accounted for barely 1% of GDP, reflecting a continental power focused on domestic development. World War II marked a historic turning point. In 1945, defense absorbed nearly 41% of GDP, marking the total militarization of the economy and the birth of the military-industrial complex symbolized by the construction of the Pentagon.
After 1945, the share of the budget fell back to around 10% of GDP, but without returning to its pre-war level. The National Security Act of 1947 institutionalized national security with the creation of the Department of Defense, the CIA, and the NSC, establishing defense as a structural pillar of government.
During the Cold War, spending fluctuated between 6% and 9% of GDP, reflecting the logic of containment and nuclear rivalry with the USSR. The end of the Cold War led to a relative disengagement: the budget fell to around 3% of GDP in the 1990s, marking the « peace dividend ». But the attacks of September 11, 2001, led to rapid rearmament: spending reached 4.8–5.7% of GDP around 2010, driven by the wars in Afghanistan and Iraq and the militarization of domestic security. In 2025, the overall budget amounted to approximately $1.365 trillion, or 4.6% of GDP. It consisted of $926.8 billion for the DoD, $372.2 billion for veterans, and $66.5 billion for foreign aid. This structural inflation can be explained by doctrinal modernization (multi-domain warfare, AI, cyber, space), rising personnel costs, and the proliferation of foreign engagements.
Beyond the numbers, US military spending has become a systemic instrument of power. It supports innovation, employment, and national competitiveness while consolidating US global leadership. Stabilized at around 4–5% of GDP, the defense budget reflects less a reduction in effort than a permanent institutionalization of war, confirming the persistence of the military-industrial complex and the centrality of defense in US governance and strategic projection.
Read more on February 1st, 2026.