The 25^th anniversary of the North Atlantic Treaty Organization was not a cheery one. It was held in Brussels, but also occurred under the shadow of Watergate. The Alliance had just been through 1973’s agonizing “Year of Europe,” during which President Richard Nixon and his Secretary of State Henry Kissinger sought and failed to reorganize Atlantic relations in response to the European Allies’ efforts to develop unified political and economic policies. By the time the heads of government met in June 1974, 1200 pages of White House transcripts had been released, and media swarmed to the summit: not because of the Alliance, but because of Nixon’s growing infamy. Other heads of government complained that the massive Secret Service presence, with its motorcades and barriers protecting Nixon, made it nearly impossible for them to travel around the city. The dominance of the president, but also his fallibility, had never been clearer.

Now, in 2019, on NATO’s 70^th anniversary, the conduct of the President of the United States is once again accompanied by discussion about the president’s actions, of special prosecutors, and talk of impeachment. Their fates and the fates of their presidencies may differ, but the Trump and Nixon presidencies are forever linked.

But there are other important comparisons to be made between Nixon and Trump, and one of the most striking is their approach to NATO. Both presidents were confronted with similar choices when it came to negotiating security and economics with allies. Both Nixon and Trump played hardball with their allies, making demands that they determined to be in their best interests. But Nixon and Trump’s methods could not be more different. Nixon’s approach was subtle, effective, and laid the basis for continued cooperation. Trump, on the other hand, has chosen to drag his disagreements into the public sphere, perhaps even picking fights solely for the sake of publicity. Unlike Nixon, there is little evidence that Trump understands how his battle with his NATO Allies will limit his ability to achieve other foreign policy priorities.

One of the most remarkable differences in the way Nixon and Trump approached the issues of economic competition and military partnership was in language. Nixon’s language, in private, was more than salty; it could be obscene and offensive. But in public, he was usually careful, purposeful, and nuanced. Where Trump has blasted NATO Allies on Twitter, Nixon was circumspect in what he and his administration said to the press. In the 1970s, it was essentially unheard of for a Cabinet official, let alone a president, to suggest that the U.S. troop deployment to Europe and American support of NATO was conditional upon European economic policies acceptable to the United States. Trump tweets about this regularly; it took a long time for Nixon to even hint at the link.

Nixon and Kissinger fretted about both economic protectionists in Congress and a growing group of Americans that, in the Vietnam years, were vocally rejecting a role for the U.S. military outside of the United States. If these two groups combined, they would form an “unholy alliance” that might threaten public support for the American commitment to NATO. In an attempt to prevent loud calls for challenging Europe on trade, Nixon sought to convince Congress that he would protect American interests, choosing as his spokesperson the decidedly undiplomatic Secretary of the Treasury John Connally.  In May 1971, Connally stunned the Allies by openly questioning the future of the Atlantic Alliance. Speaking to a bankers’ association in Munich, Connally told Europeans that Washington financed a “military shield”—NATO—that covered both America and Europe. After 25 years, “legitimate questions” had arisen over how to pay the cost of the shield, and Washington had “the right to expect more equitable trading arrangements.”

The text of Connally’s speech hardly reads like dynamite today. But it was explosive at the time. A United States principal was, for the first time, making a link between trade arrangements and the defense of Europe. Implicit in Connally’s remarks was the suggestion he or Nixon might demand economic concessions from Europe in return for an American commitment to Europe’s security. The speech ruffled feathers in Europe: NATO Allies understood immediately that the issues Connally had raised were not just about trade, but about the future of transatlantic defense relations.

The Allies waited, wondering if Nixon would repeat Connally’s threat. But he held off, at first, on making such a connection. Nixon knew there was “obviously a link between economics and political-security issues,” but he faced-down pressure from Congress and some of his advisors to make that link explicit. He was convinced that the economic relationship between the United States and Europe was about far more than “horse-trading” over “soybeans and cheese.” He warned that if “Europe should adopt a trade policy which is anti-US, it could affect attitudes in the US—bring about an unenthusiastic attitude toward Europe—and will carry over into the political area. There will be pressure to withdraw divisions and NATO would come apart.”

But efforts to bring U.S.-European trade and foreign policy into closer alignment fizzled in 1973. Kissinger observed that the U.S. had “never gone for the jugular” with the Europeans, and wondered if now was the time. Nixon ultimately settled on a less extreme strategy, and to have the President make the link between economics and security in public. In March 1974, Nixon used a speaking engagement at the Executives’ Club of Chicago to make the connection. Egged on by Kissinger, he agreed the time was right: “OK, Henry,” said Nixon; “I’ll hit them even harder than you did—for the ladies.” In Chicago, Nixon concluded the answer to an audience question with “an observation for our European friends:”

Now, the Europeans cannot have it both ways. They cannot have the United States participation and cooperation on the security front and then proceed to have confrontation and even hostility on the economic and political front.

If the Europeans were not willing to sit down and discuss the necessary cooperation, he continued, there could be no meetings of the heads of government of the West, even to celebrate NATO’s 25^th anniversary.

In the end, Nixon did attend the anniversary—even with Watergate looming in the background. The President and Secretary of State believed they had convinced the Europeans to avoid confrontational policies. After meeting with the new British Prime Minister, Harold Wilson, Kissinger told Secretary of Defense James Schlesinger: “This European thing will work out okay. They are pissing in their pants.”

Nixon and Kissinger’s crasser comments were private. They were recorded, of course, but never tweeted. When Nixon did finally decide to “hit” the Europeans in public, he used a subtle answer to signal to the European diplomats and politicians, who he knew would be listening, that he was serious.

President Trump, on the other hand, has chosen to stage a much more public fight with the Europeans, and it is not clear that his efforts to link economics and defense rests on the same strategic logic that motivated Nixon. Where Nixon had been measured in his public remarks, Trump has taken the opposite tack. After a meeting with NATO Allies, he tweeted:

The U.S. must be treated fairly, which it hasn’t, on both Military and Trade. We pay for LARGE portions of other countries military protection . . . hundreds of billions of dollars, for the great privilege of losing hundreds of billions of dollars with these same countries on trade. I told them that this situation cannot continue – It is, and always has been, ridiculously unfair to the United States.

Where Nixon had said NATO was not about soybeans and cheese, Trump has made it about tariffs on steel and aluminum, and the Europeans have responded with tariffs on “peanut butter, orange juice, and whiskey.” Trump, angered by German pipeline policy in particular, asked on Twitter, “What good is NATO if Germany is paying Russia billions of dollars for gas and energy? The U.S. is paying for Europe’s protection, then loses billions on Trade. ”

According to recent reports, Trump remains attached to plans to explicitly transform NATO into a protection racket. He is reportedly pressing for a policy of demanding that some allies pay the cost of the American presence with a 50% surcharge or premium for the privilege of hosting Americans. Recently, acting Secretary of Defense Patrick M. Shanahan contradicted this reporting, saying that U.S. policy is “not about cost-plus 50 percent” and that “We’re not going to run a business.” But the idea’s public airing certainly sent a message.

President Nixon would have approved of Shanahan’s line. Not because he had a soft spot for Europe. He was willing to make clear to the Europeans that he would defend American economic interests even at the expense of public disagreement with European Allies. But he did so in such a way that preserved the public line that American troops in NATO were not mercenaries—and he believed it was essential to preserve this argument for two reasons.

First, U.S. policymakers, especially Nixon and Kissinger, have always calculated that the American people and Congress would not support the deployment of U.S. military forces abroad as pawns. To maintain support for the NATO deployment and bases, it was essential to describe the troops as serving abroad in service of American security. Anything else would open up the deployment, and thus NATO itself, to horse trading and bargaining, and ultimately lead to their withdrawal. Make no mistake: Implicitly, as Nixon showed, the U.S. force presence in Europe and support for NATO did give Washington leverage in European capitals. But trading on this too heavily and publicly would, Nixon believed, backfire.

Second, Nixon knew that NATO ultimately served American security and foreign policy interests inside and outside of Europe: Of course, NATO was useful in keeping Europe peaceful. But, just as important, a Europe at peace allowed the United States to focus its efforts and concentrate its policy in other parts of the world. When Nixon argued for NATO against those in Congress who wanted to pull back from Europe, he told them that NATO was the “blue chip” at the center of American policy. Only by keeping Europe stable could America respond to change in the rest of the world. For Nixon, this was no mere political posturing. He believed that NATO gave him the “diplomatic wallop” necessary for his ambitious policies towards the USSR and China.

The Trump administration is, reportedly, looking for NATO support in contesting specific Chinese policies and technologies. This, however, will be difficult to do in the current climate for Trump has not presented NATO as the “blue chip” of American policy, as a source of stability and strength that allows American power to be exercised elsewhere. Instead, he has picked fights with NATO and specific NATO Allies, sparking tariff wars with both Canada and the European Union. Nixon and Kissinger feared that linking economic competition and military cooperation too closely would ultimately lead to Congress giving up on NATO. At the moment, Congress has been steadfast in its support of the Alliance. But Trump is playing with matches that even Nixon would not light.

The above draws on his Enduring Alliance: A History of NATO and the Postwar Global Order out now from Cornell University Press.