During the U.S. presidential campaign, Donald Trump frequently expressed his doubts about the usefulness of NATO. Although he said that he didn’t want the United States to pull out of the alliance, his general criticisms of it have left an indelible impression on U.S. allies, for better or worse. His more benign remarks (which others have made before him) involved lambasting the United States’ partners for not paying their fair share of NATO defense. “Only four of 28 other member countries besides America are spending the minimum required two percent on defense,” he said in April while on the campaign trail. Trump has also suggested that NATO “doesn’t really cover terrorism like it’s supposed to.”

The president-elect’s coarser attacks—such as calling NATO “obsolete”—have struck hard at NATO’s fundamentals. And more ominously, he has repeatedly made the United States’ defense guarantee a purely conditional and transactional commodity. “If they can’t pay their bills, honestly,” he declared at a campaign rally in Wisconsin and has since repeated a number of times, “they’ve got to go.” In the case of a Russian attack against the Baltic members of NATO, Trump said that the United States should come to their aid only “if they fulfill their obligations to us.” When discussing the possible withdrawal of U.S. troops, he said, “If we have to defend the United States, we can always deploy [from American soil] and it will be a lot less expensive.”

Given such statements, as well as those implying closer relations with Russian President Vladimir Putin and the inevitability of Japan and South Korea acquiring nuclear weapons, allied leaders have naturally reacted with trepidation. President Park Geun-hye of South Korea spoke with Trump only two days after the election, as NATO Secretary-General Jens Stoltenberg sought to reassure others (and possibly himself) that the alliance would remain intact. On November 17, Japanese Prime Minister Shinzo Abe flew to Trump Towers to meet with the president-elect; he was the first foreign leader to do so. In these cases and others, Trump reaffirmed the United States’ alliance commitments.

At this point, it is unclear which of Trump’s promises will come to fruition and how robust or fragile America’s transatlantic and transpacific alliance system will be in the face of new uncertainty. But the past provides some insight into how things might shake out.


Historically, formal defense alliances tended to be comparatively short-lived and were generally conditional in nature. For example, the United States formed a number of ad hoc coalitions, from the temporary alliance with France during the American Revolution to the brief period of American “co-belligerence” during World War I. After the 9/11 attacks, then Secretary of Defense Donald Rumsfeld drove home the idea that alliances were conditioned upon changing strategic circumstances. “In this war,” he wrote in an op-ed as the George W. Bush administration prepared for Iraq, “the mission will define the coalition—not the other way around.”

In this light, the post–World War II multilateral Atlantic Alliance and the hub-and-spokes alliances between the United States and key Asia Pacific partners are relatively new developments; even so, they have spanned two-thirds of a century and have proved to be both durable and highly resilient. The Atlantic Alliance weathered the transformation of the European security system from East-West confrontation to a Western-centric post–Cold War order, during which NATO conducted its first shooting wars in the Balkans; later, it intervened in Afghanistan and Libya. The alliance nearly doubled its membership at the same time. In the Asia Pacific, the focus of Washington’s hubs-and-spokes alliance system shifted from Soviet containment to balancing a rising China. The Asian and European alliances proved adept at resolving internal tensions between their member states, whether it was the deep and enduring distrust between Japan and South Korea, France’s extended exit from NATO’s military command structure between 1966 and 2009, or the nonstop burden-sharing debates.

Indeed, these alliances have proved highly robust, capable of adapting to substantial departures from the circumstances surrounding their creation. The system also comes with plenty of built-in inertia, with U.S. troops permanently deployed in Europe and Asia. The deep integration of command and control systems, the existence of shared technical and procedural standards at all levels, and the shared surveillance of the prospective battle space provides additional ballast to the alliances. Altogether, this system provides the United States with an unrivalled strategic hinterland, of the sort that China and Russia can only dream of.

That is not to say that Trump’s damaging rhetoric and the rise of populism throughout the West won’t seriously strain the alliance system. In fact, it will be tested as never before.

The issue with Trump’s campaign promises is that Washington’s partners expect American presidents, who are beholden to their electorate, to do what they say they will do. Of course, reality or plain strategic common sense can push a president in a different direction; but this is not something to bet on. Bush was not elected to invade Iraq, but 9/11 gave him the mandate to do so, even if the outcome was as unhappy as it was unexpected. Nor can foreign leaders console themselves by assuming that Trump’s antagonizing language is purely instrumental, tailored to whatever he thinks may please his audience of the moment, especially since this reading cuts both ways. This could mean that Trump’s bromides to Park or Abe were also meant to appease rather than to be taken as serious statements of intent.

Compounding the unease is the division among European members of NATO over how to respond to ongoing security challenges, such as the conflict in Ukraine. Although the United Kingdom’s position in NATO will remain unchanged, it has been an unfocused member, overwhelmed by negotiations over Brexit. The success of populism across the Western world has also made siding with Putin an important selling point for those seeking to burnish their anti-élite credentials. This has added fuel to the bonfire of antiestablishment politics as France, Germany, Italy, and the Netherlands enter into elections fraught with uncertainty. Several EU states, including as Bulgaria, the Czech Republic, and Hungary, already favor accommodating Russia while the advent of semi-authoritarian governments in Hungary and Poland have challenged the notion of shared common values within the EU and NATO. At the moment, Europe increasingly resembles a house of cards that could collapse with the slightest breeze.


The worst-case scenario is that over the next year, the multilateral alliance system in Europe will begin to unravel, with eventual knock-on effects in Asia Pacific. There are several ways in which this could unfold.

The first hinges on NATO’s plan to enhance its presence in Eastern Europe. From April to May 2017, NATO is due to roll out an “enhanced forward presence” in the Baltics and Poland, a decision made in 2016 at its summit in Warsaw. This involves, in particular, the deployment in Poland of a U.S. armed force or Stryker regiment (named after a new type of U.S. armored infantry vehicle). Countermanding this key American contribution to the enhanced forward presence would send to friends and foes alike a clear signal of U.S. disengagement.

The second is that, just as Putin challenged the United States and its allies by intervening in strategically gray areas of Ukraine (such as Crimea and Donbas), he could promote subversion in parts of the Balkans that belong to neither NATO nor the EU (such as Bosnia, Kosovo, Macedonia, and Serbia). The current enlargement of NATO to Montenegro, which is a strategically marginal piece of real estate for the EU but holds significant religious and historical value for Russia, could give Putin a reason to interfere and test American resolve. In the past, the Russian leader has responded quite aggressively whenever he feels challenged by the West: when Kosovo declared independence, Putin provoked war in Georgia by recognizing the self-proclaimed states of Southern Ossetia and Abkhazia, and when Ukraine sought regime change, Putin annexed Crimea. A crisis could also erupt in the Russian-speaking majority of Transnistria, Moldova, which Putin could use as an excuse to intervene, or over the eventual replacement of President Alexander Lukashenko in Belarus with a more pro-Russian leader.

A third way in which Trump could derail the alliance is the Iran nuclear agreement, which he has promised to scrap, to “renegotiate,” or to enforce “like you’ve never seen a contract before.” Within four to 12 months of his inauguration, Trump will have to decide whether to renew the set of executive waivers issued by the outgoing administration, which have temporarily lifted some of the sanctions against Iran. Choosing not to renew them would signal his intention to withdraw from the Joint Comprehensive Plan of Action, which would meet the combined opposition of the other signatories: China, the EU, France, Germany, Russia, and the United Kingdom.


In the face of these challenges, Europe could respond by looking for areas in which it could enhance cooperation. The defense spokesman of the German ruling Christian Democratic Union Party has suggested that France and the United Kingdom could step in to provide a nuclear guarantee to its European allies. But that has actually, albeit quietly, been the case since 1974, when the Atlantic Alliance stated that these nuclear forces contribute “to the overall strengthening of the deterrence of the Alliance in Europe.” It also strains the imagination that a viscerally anti-nuclear German population would welcome renewed and high-profile reliance on nuclear deterrence.

Thus, a more likely reaction to the loss of a U.S. security guarantee is for Europe to hedge against possible Russian pressure by enacting pro-Russian policies, such as reinforcing the pro-Russian trend set by Hungary and the Czech Republic after the annexation of Crimea in 2014. There might also be a shift from a multilateral NATO to bespoke bilateral pacts between European nations and the United States. In such a Europe, Russia would have plenty of room to go well beyond the bounds of the post–Cold War Commonwealth of Independent States in trying to wield influence.

The United States’ East Asian partners would no doubt draw similar lessons, seeking to hedge on their security policies toward China—the new, pro-China policies of a long-standing U.S. ally such as the Philippines is an early example. They may also look to fortify their national defense policies and countries that have considered adopting nuclear weapons in the past, such as Australia and South Korea, might seek to acquire them.

Of course, none of this is inevitable. But Trump has helped make such a scenario a distinct possibility. The incoming U.S. administration will have to act carefully and swiftly in order to forestall such processes. But whether the untested new commander in chief and his national security team can be both careful and swift is anybody’s guess. What is certain is that the stakes for global stability and the continuation of U.S. power and influence could hardly be higher. 

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  • FRANÇOIS HESIBOURG is Chair of the International Institute for Strategic Studies and a Special Adviser at Fondation pour la Recherche Stratégique.
  • More By François Heisbourg