From the 1990s onwards, military expenditure saw a general decline as the Cold War ended and the U.S. focused on domestic issues. However, the attacks on September 11, 2001, and the subsequent War on Terror led to a significant spike in defense spending, which remained elevated throughout the 2000s and 2010s, peaking at 4.9% of GDP in the early 2000s. By 2020, defense spending stabilized at about 3.7%, reflecting the U.S.'s ongoing military commitments and its shifting global priorities. In recent years, military expenditure has remained steady at 3.5% in 2021-2022, continuing the trend of prioritizing defense while navigating global challenges like the rise of China and regional instability.
For a broader context, visit other statistics on US population growth rate, Service sector’s share in US GDP, United States military personnel proportion.