The Key Lessons of America’s Recent Wars: Failing or Losing in Grand Strategic Terms

America’s defeat in Afghanistan has launched another round of official studies of the lessons of war. Such efforts have had value in the past by examining the military lessons of a given war and some of the major political decisions and programs that shaped its course. At the same time, most such efforts have understated or ignored critical failures in conducting the broader course of the war and in moving to a successful and stable peace. They have ignored U.S. failures to set meaningful grand strategic goals for engaging in a given war to properly evaluate the value of sustaining America’s role in combat, and to terminate the war in ways that could credibly result in lasting and meaningful peace.

This analysis examines each of America’s grand strategic failures in warfighting since 1945 and its failures to learn the right lessons from these wars. It indicates that other failures included a common tendency to define strategy in terms of broad goals rather than as a practical process that justified such goals, created practical plans to achieve them, and allocated the needed resources with proper management and honest and objective measurements of their effectiveness.

It shows that the United States failed to adequately perform strategic triage in assessing the costs and risks of engaging in combat and sustaining this role over time. The United States often began what became a major military engagement by using U.S. forces in advisory roles or low levels of combat. It then escalated to full-scale warfare without properly assessing the costs and risks of escalating U.S. involvement and the probability of ending a conflict with a lasting grand strategic victory.

It also shows that the United States failed to properly address the risks created by failed host-country governance, a lack of effective host-country political leadership and unity, and deep divisions that existed at an ethnic, tribal, and religious level. It underestimated the problems in creating effective host country forces as well as creating an effective rule of law and local security. It treated corruption and authoritarian self-interest as secondary problems rather than as major challenges to success. In the cases of Vietnam, Iraq, and Afghanistan, it also attempted to create the shell of a democratic government as a potential solution to nation-building problems regardless of real-world political divisions, inexperienced leaders, and weak overall structure of governance.

This report is entitled The Key Lessons of America’s Recent Wars: Failing or Losing in Grand Strategic Terms and is available on the CSIS website at https://csis-website-prod.s3.amazonaws.com/s3fs-public/2023-06/230613_Cordesman_Lessons_AmericasWar.pdf?VersionId=x9i2aJLVWaHnwOtUW6f0v9BIsgxDzxtk.