The U.S. defense budget serves as a tangible reflection of the country's military strategy, global commitments, and geopolitical challenges. An analysis of its evolution offers an insight into the U.S.'s shifting defense priorities and its interpretation of threats and challenges.

The U.S. Department of Defense, in conjunction with the Congressional Budget Office, develops the Future Years Defense Program (FYDP). This plan outlines the department's intentions and financial projections for the next five years. The FYDP for 2023-2027 was devised in 2022, considering the then-prevailing geopolitical landscape.

In President's proposed budget for 2023, the Department of Defense (DoD) requested $772 billion. This amount represents a reduction of about 1.5% in real terms compared to the appropriations of 2022. The budgets projected for 2024 and 2025 stand at $784 billion and $762 billion, respectively. The defense expenditures in 2022 accounted for 3.6% of GDP, marking the lowest level since 1939 and lower than in 2000 (3.8%) before the Middle East engagements. In 2023, defense spending could drop to 3.3% of GDP, setting a new record low.

Contrasting the current trends with historical spending patterns paints a vivid picture:

• During World War II, when the United States was actively involved from December 1941 to September 1945, defense spending accounted for 33% of GDP, peaking at 43% in 1944.
• The Korean War, lasting from June 1950 to July 1953, saw defense expenditures averaging 12.9% of GDP, with a peak of 15.7% in 1953.
• The Vietnam War, which stretched from August 1964 to April 1975, witnessed an average defense spending of 9% of GDP, with a high point of 11% in 1967.
• More recently, the invasion of Iraq, the war in Afghanistan, and the presence in Syria from October 2001 through August 2021 (with the active phase until 2011) saw an average defense spending of 4.8% of GDP, and a maximum of 5.5% in 2010.

These past episodes illustrate that defense spending can significantly vary depending on the global conflicts and national security challenges the U.S. faces. The current defense budget allocations, as compared to these historic events, indicate a shift in U.S. defense strategy, reflecting changing geopolitical realities and potentially a focus on different forms of defense and warfare strategies.

In conclusion, the evolving trends in U.S. defense budget, combined with the historical perspective, suggest that the country does not perceive the geopolitical challenges concerning Russia and/or China as immediate threats warranting an increase in defense spending. Whether this indicative complacency is a reflection of confidence in existing capabilities or a precursor to a more covertly intensive preparation is a matter of conjecture and remains to be seen.