The American nuclear umbrella has monopolized attention recently in the ongoing debate about Europe’s security architecture. This renewed interest is unsurprising, given the hostility that many Trump administration officials appear to harbor for America’s NATO allies.
The White House has certainly done itself few favors, openly questioning Europe’s value to U.S. interests. And recent reports that the Department of Defense is considering withdrawing 10,000 troops from the continent raises the prospect that the American contribution to NATO will rely increasingly on nuclear weapons.
However, it is important not to lose sight of the irreplaceable role of conventional forces — particularly those forward-deployed by the U.S. Unfortunately, this conventional factor is too often overlooked by some in the Trump administration.
The rationale for a dramatic drawdown of U.S. conventional forces in Europe rests on the idea that China poses the gravest and most immediate threat to U.S. national security. Since the U.S. finds itself in an era of resource scarcity and suffers from a deficient defense-industrial base, Washington — so the argument goes — must prioritize Asia and leave Europe’s security mostly to the Europeans. The “prioritizers” in the Trump administration therefore argue that most if not all of America’s war-fighting assets must be reallocated to Asia. The U.S. contribution to NATO, by necessity, will have to rely mainly on extended nuclear deterrence moving forward.
To be sure, the self-described prioritizers deserve credit for highlighting the gravity of the looming Chinese threat. The U.S. does find itself in a period of resource scarcity. It might have to shift some war-fighting assets from Europe to Asia. And, in the near term, Washington and its NATO allies might have to rely more on nuclear employment if one or more members of the Axis of Aggression engage in opportunistic or coordinated aggression across the vast Eurasian rimland.
Nevertheless, a precipitous withdrawal of U.S. conventional forces in Europe would upend the Trump administration’s effort to prioritize China. Limiting the U.S. role in NATO to one primarily of nuclear deterrence would open up opportunities for Russia to sow division within the transatlantic alliance, and possibly salami slice its way into the Baltic or Nordic countries.
Let’s take the last concern about Russia and NATO cohesion first. For a U.S. president to order even a limited nuclear strike on Russian territory with a low-yield tactical warhead, he or she would be risking escalation to an intercontinental exchange, and possibly the loss of millions of American lives. Should nuclear warfare erupt in Europe, New York City or Chicago would not immediately be at risk of devastation, but the risk is not zero and should surely give any president pause.
That is why U.S. policy has traditionally relied on a forward conventional defense to establish non-nuclear escalation barriers. Washington has long tried to raise the nuclear threshold in Europe precisely to bring credibility to its nuclear umbrella.
This being the case, would greater U.S. reliance on nuclear weapons at the expense of conventional forces reassure Europe that Washington still has its back? Would the NATO allies really trust an American president — especially one who regularly questions their value — to run such grave risks for a supposedly “secondary” theater?
The evidence suggests not.
In response to reports about the possible drawdown of U.S. troops, the Lithuanian president’s national security adviser, Deividas Matulionis, highlighted the critical role of America’s forward conventional presence. It is the rotation of U.S. combat forces through the Baltics, he stressed, that provides a key deterrent to Russian aggression.
A Polish official recently echoed this sentiment, noting that the departure of American troops “would send a signal to Russia that [Eastern Europe] is a gray zone for Washington,” thus inviting Russian predations.
A deterrence failure in Europe that escalates to the U.S. trading nuclear shots with Russia would surely pull American resources away from Asia — especially if the U.S. homeland were to come under strategic attack. It is hard to see how, in such a scenario, vast numbers of U.S. troops would not be drawn back to the continent. Moreover, if Europe were to lose faith in the U.S., Washington could very well lose a vital partner in the peacetime competition against China.
The U.S., after all, still needs Europe to help seal off Beijing’s access to technologies like advanced semiconductors. It will also need Europe’s defense-industrial cooperation to better compete against Beijing and procure military hardware more efficiently and at greater scale. And, if deterrence should fail in the western Pacific, Europe has impressive undersea warfare capabilities that could make a serious contribution in bottling up the Chinese navy in the western Pacific.
Put simply, there are no shortcuts. Because the Asian and European theaters are so closely intertwined, Washington cannot simply strip Europe of war-fighting capability and magically arrive at a more robust deterrence posture in Asia.
However, if U.S. officials recognize the interdependence between conventional and nuclear deterrence, they can better assess where tradeoffs between those two theaters might exist and then make the necessary hard choices. Effectively allocating resources across Eurasia will depend on nothing less.
Thus, to ignore the conventional factor in nuclear deterrence would be to raise the threshold for U.S. involvement in Europe while lowering the threshold for Russian aggression, all the while weakening deterrence in Asia.
Prioritization is a necessary ingredient in any sound strategy. However, for a global power like the U.S., prioritization can hardly be construed as an ingredient for deciding in which theater to skirt responsibility. Such an approach would constitute throwing strategy making to the wind.
Kyle Balzer is a Jeane Kirkpatrick Fellow at the American Enterprise Institute.
