Nato is having a rough summer. Fresh off United States President Donald Trump’s deliberately disruptive behaviour at the alliance summit last month, Nato has suffered a high-stakes blowup between two key members: the US and Turkey.

That dispute crystallised over the fate of an American pastor, Andrew Brunson, being held in Turkey on spurious charges of supporting a failed coup against Turkish President Recep Tayyip Erdogan in 2016. It has been punctuated by economic sanctions, escalating threats and counter-threats, and speculation that Turkey might punish Washington by aligning itself with Moscow.

Yet, the problems between the US and Turkey run much deeper than the dispute over Brunson, and go back for many years. Likewise, the problems Nato confronts run deeper than the unique challenges posed by a US president with no love for Atlanticism. Nato is facing a series of bigger structural challenges. Trump did not cause these problems, but he is not making them any easier to solve, either.

The US-Turkey crackup is a good illustration. It erupted on Trump’s watch, and he has not handled it particularly well: By publicly condemning Turkey, and by implying that the punitive tariffs he imposed on Turkish imports will not be removed even if Brunson is released, Trump has given Ankara little incentive or pathway to resolve the crisis in a way favourable to Washington.

But, the US-Turkey relationship was destined for trouble even before Trump took office. The combination of America’s counter-Daesh campaign (which relied heavily on Syrian Kurdish groups that the Turkish government considers mortal enemies), Erdogan’s increasing authoritarianism and anti-Americanism, Ankara’s decision to purchase sophisticated air defence systems from Russia, and widespread — albeit incorrect — Turkish suspicions the US was behind the July 2016 coup attempt was pushing matters toward a crisis regardless of who occupied the White House.

Something similar could be said of Nato writ large. To be sure, Trump has injected a new level of distrust and discord into the relationship, above all by evincing disdain for Nato’s founding premise: That the US and its allies can better promote their security and prosperity together. But one of the reasons Trump’s behaviour has proven so destabilising is that he inherited an alliance that was experiencing several accumulating strains.

First is the crisis of burden-sharing, to which Trump has often pointed. The US president is wrong to say the allies are simply sucking the wealth and vitality out of the US, and it would be profoundly dangerous if Europe reverted to a situation in which arms races and security competitions were rampant. But something is undoubtedly wrong when three of the richest countries in the world — France, Germany and the UK — would struggle to deploy and sustain a single brigade if Russia attacked the Baltic nations. After the Cold War, too many Nato countries aggressively dis-invested in defence. Russian President Vladimir Putin has subsequently reminded them what military power is for, but the alliance faces a long road back from its post-Cold War atrophy.

Second, even before Trump was elected, Nato was being tested by the alliance’s shifting threat geography. During the Cold War, an aggressive Soviet Union was everyone’s problem: There would be nowhere to hide if war broke out. Today, however, Nato has expanded and the Russian military threat is more concentrated in Eastern Europe, so the fundamental cohesion that a shared, overarching danger creates has faded.

Countries on the eastern flank still see Russia as an existential threat, but countries in Nato’s south are more fearful of terrorism and migration flows. Although these southern countries do worry about Russian electoral meddling and information warfare, they are often less supportive of economic sanctions and other aspects of a more assertive posture toward Moscow. Two of these allies — Greece and Italy — have been particularly eager to get back to business with Putin, in hopes of increasing economic ties to Russia.

Third, US relations with Nato are being tested by the fact that even amid renewed Russian aggression, the alliance is simply no longer as central to global affairs or US strategy as it once was. The proportion of global gross domestic product and military spending Europe accounts for has steadily declined relative to Asia’s share. Moreover, the greatest long-term threat to US security and influence is not found in Europe, but on the other side of the world.

The Nato allies are simply not positioned to help Washington deal with the rise of China in the way that they helped it deal with Moscow during the Cold War, or even with post-Cold War threats in the Middle East. This inability unavoidably makes Nato loom somewhat smaller in American statecraft; it makes it easier for Trump to argue — incorrectly — that the alliance is “obsolete”.

Fourth, Nato is being lashed by severe political instability on both sides of the Atlantic. From Washington and London to Paris and Rome, establishment parties and politicians are losing ground to populists and other formerly fringe figures. This instability is already weakening Nato in some respects — an inward-focused United Kingdom, consumed by Brexit, is less useful than a confident, outward-facing country.

More troubling still, a resurgence of authoritarian and quasi-authoritarian politics is roiling countries such as Turkey, Hungary and Poland. In some cases, these governments have evinced admiration for Putin as a fellow right-wing authoritarian, raising questions about how effectively the alliance can combat Russian revisionism. The authoritarian resurgence within Nato is also testing the proposition that the alliance is united not just by shared geopolitical interests but shared political values.

Finally, if the advent of Trump has left many Europeans deeply concerned about US judgement and policies, these concerns were building well before Trump arrived. During the presidency of George W. Bush, many Europeans were aghast at what they deemed abrasive, unilateral and destabilising American policies, particularly the invasion of Iraq. During the years of Barack Obama, many European Atlanticists worried that the US was pulling back from global leadership. The Syria red-line incident in 2013, when Obama declined to use force against Bashar Al Assad in response to massive chemical weapons attacks on Syrian civilians, was particularly searing in this regard. If Trump’s presidency has proven so alarming to European observers, it is because he seems to combine the unilateralism and the strategic diffidence they disliked in Bush and Obama.

None of this is to say that Nato is doomed. The alliance would not have survived for nearly 70 years were it not inherently resilient and deeply institutionalised. It remains the single most powerful geopolitical coalition in the world. And there remain plenty of issues where trans-Atlantic cooperation is needed: Restraining Russia, addressing instability in the Middle East and North Africa, countering Chinese economic coercion, and others.

This is why committed Atlanticists in the US and Europe have been working so diligently to preserve and strengthen the alliance. Those efforts have hardly been fruitless: To give just one example, Nato has actually been making painfully slow but nonetheless discernible progress in creating a meaningful deterrent to Russian aggression in Eastern Europe.

Yet, this is where Trump’s role is so problematic. Today as in the past, dealing with the major challenges Nato faces requires strong political leadership from the alliance’s key members. In particular, it requires that the US — the indispensable catalyst of collective action - play an assertive role in standing up for NATO’s values and interests, and in uniting rather than dividing the alliance. Trump has little apparent interest in playing this role; any increases in defence spending he cajoles out of the Europeans are likely to be outweighed by the doubts he is sowing about US intentions and competence, and by the havoc he is wreaking whenever Nato gathers.

Trump can rightfully complain that the alliance was entering stormy seas even before he took the helm. He cannot evade responsibility for his failure to act as the captain Nato needs right now.

— Bloomberg

Hal Brands is a Bloomberg Opinion columnist. He is the Henry Kissinger Distinguished Professor at Johns Hopkins University’s School of Advanced International Studies and a senior fellow at the Center for Strategic and Budgetary Assessments. His newest book is American Grand Strategy in the Age of Trump.