“I give you my solemn warning that under the present trend, the next world war is inevitable,” declared the French military leader Ferdinand Foch. It was 1921, and Foch, the commander in chief of the Allied armies during World War I, was raising alarms in a speech from New York City. His concern was simple. After defeating Germany, the Allied powers had forced it to disarm with the Treaty of Versailles. But just a couple of years later, they had stopped enforcing the terms of their victory. Berlin, Foch warned, thus could and would rebuild its military. “If the Allies continue their present indifference . . . Germany will surely rise in arms again.”

Foch’s comments proved prescient. By the late 1930s, Germany had indeed rebuilt its military. It seized Austria, then Czechoslovakia, and then Poland, sparking World War II. When it was again defeated, the Allies were more attentive in their management of the country. They occupied and divided it, disbanded its armed forces, and largely abolished its defense industry. When the United States and the Soviet Union allowed West Germany and East Germany, respectively, to reestablish their militaries, it was only under strict oversight. When they allowed the halves to merge, Germany had to limit the size of its armed forces. Even so, British Prime Minister Margaret Thatcher opposed reunification, fearing it would produce a dangerously powerful country. A bigger Germany, she warned in 1989, “would undermine the stability of the whole international situation and could endanger our security.”

Today, Foch’s and Thatcher’s fears seem to belong to ancient history. As Europe has navigated one crisis after another in recent decades—most important, Russia’s aggression against Ukraine—the continent’s officials have worried not that Berlin might become too strong but that it is far too weak. “I fear German power less than German inaction,” declared Radoslaw Sikorski, Poland’s foreign minister, in 2011, during Europe’s financial crisis. It was a remarkable statement coming from a Polish official, given that Warsaw has traditionally been one of the governments most worried about German power. He is hardly alone: Germany’s military must “spend more and produce more,” declared NATO Secretary-General Mark Rutte in 2024.

Now, these leaders are getting what they wanted. After many delays, Germany’s Zeitenwende—its 2022 promise to become one of Europe’s defense leaders—is finally becoming a reality. In 2025, Germany spent more on defense than any other European country in absolute terms. Its military budget today ranks fourth in the world, just after Russia’s. Annual military spending is expected to reach $189 billion in 2029, more than triple what it was in 2022. Germany is even considering a return to mandatory conscription if its military, the Bundeswehr, cannot attract enough voluntary recruits. Should the country stay the course, it will again be a great military power before 2030.

People in Europe have largely been happy to see Berlin rebuild its military to defend against Russia. But they should be careful what they wish for. Today’s Germany has pledged to use its outsize armed power to help all of Europe. But left unchecked, German military dominance might eventually foster divisions within the continent. France remains uneasy about the fact that its neighbor is becoming a major military power—as are many people in Poland, despite Sikorski’s sentiments. As Berlin ascends, suspicion and mistrust could grow. In the worst-case scenario, competition might return. France, Poland, and other states could attempt to counterbalance Germany, which would divert attention away from Russia and leave Europe divided and vulnerable. France, in particular, may seek to reassert itself as the continent’s leading military power and “grande nation.” This could prompt outright rivalry with Berlin and place Europe at odds with itself.

Such nightmarish outcomes are especially likely if Germany ends up being governed by the far-right Alternative for Germany (AfD), which is rising in the polls. The intensely nationalistic party has long been critical of the European Union and NATO, and some of its members have made revanchist claims about the territory of neighboring countries. An AfD-controlled Germany might use its power to bully or coerce other countries, leading to tensions and conflict.

Berlin does need to build up its military. The continent is in danger, and no other European government has the fiscal capacity that Germany can bring to bear. But Berlin must recognize the risks that accompany its strengths and restrain German power by embedding its defensive might in more deeply integrated European military structures. Germany’s European neighbors, for their part, should make clear what kind of defense integration they would like to see. Otherwise, German rearmament could very well yield a Europe that is more divided, mistrustful, and weaker—exactly the opposite of what Berlin now hopes to achieve.

For many, it is hard to understand why Germany’s rearmament could lead to competition and instability in Europe. All Europeans are familiar, of course, with the country’s militaristic history. But in the decades after World War II, Germany integrated both its economy and its defense apparatus deeply into Europe. West Germany’s first postwar chancellor, Konrad Adenauer, firmly rejected the idea of turning his country into an independent military power and advocated integrating the West German armed forces either into a European army or into NATO. After the end of the Cold War, Germany adopted an approach of military restraint and identified itself as a “civilian power”—one that was trustworthy and nonthreatening, even as reunification made it far stronger. As Helmut Kohl, the first leader of reunified Germany, declared in 1989, “Only peace may come from German........

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