The United States has experienced losses and defeats in wars, but the extent to which these are considered outright "lost wars" depends on the context and criteria used. Notable wars where the U.S. did not achieve its strategic or political goals and is often considered to have lost include:

• The Vietnam War (1955-1975), where despite tactical victories, the U.S. failed to prevent communist takeover in South Vietnam and withdrew under pressure.
• The War of 1812, where the U.S. failed to achieve its invasion goals against British Canada, and key locations like Washington, D.C. were burned by British forces.
• The Korean War, which ended in an armistice rather than a clear victory, effectively a stalemate.
• The War in Afghanistan (2001-2021), ending with the U.S. withdrawal and the Taliban regaining control.

There are also other conflicts and battles considered defeats or setbacks for the U.S. military. However, the U.S. has had many military successes and victories in other wars such as the Revolutionary War, World War I and II, the Gulf War, and others. Therefore, while the U.S. has lost some wars in terms of failing to meet objectives or achieving unfavorable political outcomes, it has not simply "never lost a war." It is more accurate to say the U.S. has had both military victories and strategic defeats in its history.