The value of commerce at sea can no longer be measured purely in terms of the cargo in merchant ships’ holds. The combined value of oil rigs, wellheads, pumping stations and fiber-optic cables along the U.S. continental shelves runs into the trillions of dollars. Many of these assets are, in military parlance, relatively soft or vulnerable targets.

In recent years, the U.S. military has lost its near-monopoly in guided, or smart, weapons to major states like China. In the coming years, even non-state groups seem likely to acquire guided mortars and rockets. As they do, it will transform irregular warfare, making military operations in the developing world far more risky than they are today.

In brief, the spread of guided weapons, the proliferation of nuclear weapons to unstable states in the developing world and the rapidly growing menace of cyber warfare suggest a future in which the U.S. military’s current ways of projecting power and defending the American homeland are likely to be severely challenged.

Arguably the U.S. has not confronted such a combination of growing security challenges from such a weak economic position since the 1930s. And although history rarely repeats itself, it often “rhymes.”

Before the next secretary of defense calls in his green eyeshade staff, as he undoubtedly must and will, he should first have some sense of how — or if — the U.S. military can meet the challenges outlined above, and the implications for the defense program.

Absent such an effort, there is a high risk that false economies will be realized while our military remains organized, trained and equipped to meet the familiar, comfortable challenges our rivals are abandoning in favor of those described above.

As Sir Francis Bacon observed, “He who will not apply new remedies must expect new evils.”