The theme of Frederick W. Kagan’s contribution to our series “Lengthened Shadows: America and Its Institutions in the Twenty-first Century” may be summed up in the venerable motto of the Boy Scouts: “Be Prepared.” Mr. Kagan offers a brilliant and sobering look at the institution of America’s military. He writes at a moment not only when the armed forces of the United States are deeply engaged in a war against terrorism, but also when the structure and strategic rationale of America’s military is in the process of being transformed. New technology, new thinking about the best way to equip and deploy America’s military forces, and new political realities as America’s role on the world stage shifts in the aftermath of the Cold War have conspired to make this transformation of the American military an urgent item on today’s political agenda. Especially since the terrorist attacks of 9/11, America’s military obligations have grown exponentially: Have our military infrastructure and our tactical understanding kept pace with the new demands which world events have placed upon us?

It is often said that generals base their strategic assumptions more on past conflicts than current exigencies. As we move into the dangerous terra incognita of the twenty-first century, few decisions will be as important as those affecting our military preparedness. Mr. Kagan’s reflections offer an incisive analysis of what we are doing—and what we are failing to do—to meet this essential challenge.