German Chancellor Angela Merkel and French President Emmanuel Macron address the media during a news conference in the German chancellery on Volkstrauertag, Germany's national day of mourning for victims of war, on Nov. 18 in Berlin. (Michele Tantussi/Getty Images)
Leon Kohl is a graduate student in modern European history at the University of Cambridge.

President Trump has denounced French President Emmanuel Macron’s plans to create a European Union army to protect Europeans “against China, Russia and even the United States of America.” Trump derisively remarked that the French would be speaking German nowadays if not for U.S. intervention in the two world wars.

Trump’s undiplomatic rebuke of Macron was uniquely Trumpian, but the policy he espoused was one advocated by American leaders across the political spectrum in recent decades. In the 1970s, administrations from both parties were skeptical of European initiatives to create a forum to express foreign policy positions distinct from and at odds with the United States. In the 1980s, the Reagan administration feared that the reactivation of the Western European Union would undermine NATO, and the George H.W. Bush administration warned that there be no “ganging up” against the United States. Even Europhiles such as Bill Clinton remained skeptical of a Common European Security and Defense Policy.

But during the early Cold War, when figures such as Harry Truman adamantly demanded Europeans share the burden of the Western bloc’s common defense, attitudes were very different. In fact, the United States firmly supported the most ambitious and comprehensive attempt to create a European army to date: the European Defense Community (EDC). The 1952 treaty establishing the EDC envisaged the creation of a Pan-European army of 100,000 men supervised by a minister of defense accountable to a European Parliament and endowed with a common budget.

Truman understood then a reality confronting Trump now: Securing European resources for defense will require accepting a more autonomous and assertive European voice in the transatlantic defense architecture.

In 1950, alarm over what they perceived to be an aggressive and expansionist Soviet foreign policy prompted American policymakers to look to bolster Western European states as anti-Communist bulwarks.

But for domestic political reasons, the Truman administration wanted to do so without further expanding its financial and military commitments in Europe. Instead, American policymakers demanded that their European allies, including, controversially, West Germany, rearm as part of the North Atlantic Treaty framework.

But such plans sparked bitter opposition from Europeans. France in particular feared that West German rearmament could lead to a revival of German militarism and discourage the West German government from focusing on economic integration.

In the face of American insistence, however, Jean Monnet, one of the E.U.’s founding fathers, and French Prime Minister René Pleven proposed an alternative plan for a European army. The underlying idea of the EDC was that integrating West Germany into a supranational framework could offset the downsides of German rearmament. Moreover, Monnet hoped to be able to kick-start the process of European political and economic integration through the creation of a common defense force.

The Truman administration initially balked at the Pleven plan, fearing it would undermine NATO, take too long to establish and potentially alienate the West German government. Negotiations resulted in a compromise stressing the complimentary nature of the American and French visions. Any future European defense force would remain under the NATO umbrella — giving the NATO supreme commander ultimate military control and allowing NATO oversight of the EDC’s strategic planning.

Despite this NATO influence, the EDC was to enjoy a considerable degree of operational and strategic autonomy — greater than today’s E.U. has.

And yet, American policymakers soon became the leading proponents of the EDC, seeing it as a complement, rather than a competitor, to NATO. NATO Supreme Commander General Dwight D. Eisenhower convinced Truman that a European army offered the only means of harnessing Germany’s military potential for the defense of the West without snubbing Europeans’ security concerns. For Eisenhower, the EDC presented an opportunity to reduce U.S. military and financial commitments in Europe, something demanded by the political right at home. Subsuming West Germany into a European political, economic and military superstructure would also tie West Germany to the West and protect against Soviet attempts to lure it into neutrality.

The treaty establishing the EDC was signed May 27, 1952. But a change in power in France soon transformed the French into staunch opponents of the EDC and ground the initiative to a halt.

Both right-wing Gaullist and socialist forces in the French Parliament objected to the EDC, because they opposed German rearmament and feared a loss of national sovereignty. Moreover, these French critics saw European political integration as a threat to France’s global ambitions.

The United States worked to overcome this opposition and pushed its European allies to ratify the treaty. Yet despite warnings from now-President Eisenhower and Secretary of State John Foster Dulles that an “agonizing reappraisal” of American commitment to the defense of Europe could occur if Europeans rejected the EDC proposal, the French refused to budge. They doubted the credibility of the American threats given the substantial increase in the U.S. military presence in Europe at the time. And so, the French National Assembly rejected the EDC treaty on Aug. 30, 1954.

This defeat heralded the end of American support for closer European integration in the defense sphere. Over time, Americans came to view pushes to create common European foreign, security and defense structures as attempts to decouple Europe from the rest of the Atlantic alliance and undermine NATO. This belief gained traction after French President Charles de Gaulle sought to create a European counterweight to the Anglo-American and Soviet superpower blocs following his return to power in 1958 — a policy which culminated in France’s withdrawal from NATO’s Military Command Structure in 1966.

Since then, American administrations have suspected that plans for European defense integration have been motivated by anti-Americanism and feared that the creation of defense structures separate from NATO could lead to unnecessary and inefficient duplication of effort.

Today, Trump’s administration faces similar challenges as those facing the Truman and Eisenhower administrations in the 1950s.

European countries continue to rely on American forces to ensure their defense. Moreover, the heavy shadow of German militarism looms large. While Germany has been a NATO member since 1955, the E.U.’s largest and most powerful member state remains reluctant to invest significantly more in its defense unless such a policy is pursued in a European framework. Investment in a European army can be framed as strengthening the European integration project and gaining greater independence from the United States — aims largely supported by opponents of higher national defense spending and critics of Germany’s national army, which has been grappling with growing right-wing extremism in its ranks.

If the Trump administration is serious about getting the United States’ European allies to commit to greater burden-sharing, it must discard the idea that the creation of a European army threatens American interests. With France having returned to being a full member of NATO and more Atlanticist E.U. member states such as the United Kingdom, the Netherlands and Germany continuously stressing the need for close military relations with the United States and NATO, it is unlikely that a European army would become a counterbalance to the United States or damage NATO.

And so, the ethos that drove American policymakers to push the EDC in the 1950s matters today. Europeans will not agree to contribute greater resources without increased strategic autonomy and a more independent voice in the alliance in return.

While American opposition has been only one of a number of factors preventing the creation of a European army, active American encouragement of greater European defense cooperation could help policymakers overcome other challenges. Although American policymakers are rightly skeptical of the anti-American undertones of the current debate, they should welcome moves seeking to strengthen the European pillar of the transatlantic security framework.