BRUSSELS—Full details of the Obama administration’s new look in defense spending, force posture, and strategy are not yet out. But enough has been revealed  to venture some thoughts on the logic of the new approach and the longer-term implications for the United States and transatlantic partners.

The shift to a “one war, spoil and manage” strategy contrasts sharply with a decade of costly and inconclusive engagement in irregular warfare in Afghanistan and Iraq. Enormous efforts were undertaken to adapt the U.S. way of war and to focus it on counterterrorism and counterinsurgency, with the unfortunate effect of eroding the United States’ capacity to address more serious and potentially more demanding long-term challenges, above all in Asia. Today, much of the U.S. strategic community has come to believe that a disproportionate amount of effort has been devoted to meeting nonexistential threats to the national interest and international security.

A strategy re-emphasizing core risks, and conventional rather than irregular warfare, simply makes sense against a backdrop of stark resource constraints. The need to meet serious conventional contingencies with smaller ground forces could spell a renaissance in nuclear strategy. There are precedents for this in the Cold War experience, when the expense and difficulty of forward defense in Europe compelled a reliance on nuclear forces and nuclear deterrence to fill the gap at reasonable cost. Of course, we are unlikely to see a return to a doctrine of massive retaliation to meet security challenges in Asia, a more competitive relationship with Russia, or an aggressive Iran.

But the mix of conventional and nuclear deterrence in U.S. strategy could well change as forces are realigned and forward-deployed forces, in particular, become more exposed to ballistic missile attack, perhaps nuclear-armed. Under these conditions, planners may be tempted to reinforce the nuclear dimension.

Not quite a trip-wire strategy, but perhaps a bit closer than many U.S. allies would prefer. Many will be tempted to interpret the Obama administration’s new strategy as a shift away from European defense—and perhaps more important, European defense partnerships—in the face of more pressing challenges in Asia.

This interpretation is too dramatic. In reality, the shift away from European defense per se has been underway for two decades. This is not just a question of land forces. The U.S. Sixth Fleet has not kept an aircraft carrier battle group in the Mediterranean for many years. Residual U.S. forces in and around Europe are kept there to enable the United States to meet contingencies elsewhere, across the Mediterranean, the Black Sea, and the Middle East.

Maintaining a capacity to reinforce Europe’s crisis response capabilities on the European periphery, as in Libya, will continue to depend, above all, on mainly bilateral base access and over-flight arrangements. If anything, transatlantic partners will now have an even greater stake in solidifying these strategic ties. The locus of strategic risk may be shifting; the logic of cooperation endures.

Dr. Ian O. Lesser is the Executive Director of the German Marshall Fund’s Transatlantic Center in Brussels.