By Ian Bremmer
June 16, 2016

For decades, the transatlantic partnership has been crucial to international security and the stability of the global economy. Through organizations like NATO, U.S. and European leaders have worked together to advance democracy, liberty, rule of law and the market-based values that have helped lift hundreds of millions of people out of poverty around the world. There has never been a greater alliance of capable and like-minded partners.

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But today that alliance is weaker and less influential than at any other time since the 1930s. Americans and Europeans are distracted by challenges at home. Anger at government and public anxiety over the impact of globalization are on the rise. Emerging powers in Asia and elsewhere are asserting new values, and the U.S. and Europe are increasingly at odds over how best to adapt to a changing world.

Neither side seems to realize that an alliance that has been the backbone of the postwar era is crumbling. Europe is preoccupied with internal challenges like the migrant crisis, the upcoming referendum on Britain’s membership in the E.U. and ongoing disputes with Russia. In the U.S. presidential campaign, the transatlantic relationship has been less than an afterthought, overshadowed by antitrade rhetoric over China and posturing about American greatness. The horrific mass shooting in Orlando on June 12 and its possible connection to ISIS will only demand more attention from an exhausted and angry electorate.

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Yet the decades-old U.S.-Europe partnership remains essential. “Globalization seems to have made the Atlantic wider, when it needs to become smaller,” says former British Foreign Secretary David Miliband. “A multipolar world does not diminish the need for transatlantic cooperation. It enhances it. From the pivot to Asia, which is necessary on both sides of the Atlantic, to the management of the global commons, shared values need to be turned into shared priorities.”

The transatlantic rift has been years in the making. In the 1990s, the war in the former Yugoslavia generated intense resentment among Americans who were frustrated that Europeans depended on the U.S. to solve European security problems. The U.S. invasion of Iraq in 2003 provoked unprecedented resistance from France and Germany. The global financial crisis stoked European skepticism of U.S.-style laissez-faire capitalism. The U.S. National Security Agency was caught spying on friendly governments, including European ones, raising fears that American Internet companies had given U.S. intelligence agencies deep access to European secrets–which led German Chancellor Angela Merkel and others to call for a European Internet walled off from the U.S.

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Yet these events are symptoms, not sources, of the cancer infecting transatlantic relations. The problem is that there is no credible Cold War–scale rival to unite the U.S. and Europe in the face of a common threat. China is no democracy, and the state plays a heavy role in its economy, but there is a deep economic interdependence in its relations with both the U.S. and Europe. Russia can cause trouble, but it lacks the Soviet Union’s global military reach and broad ideological appeal. Without an existential enemy, it’s easy to imagine that it’s not worth the trouble to bring the U.S. and Europe together.

And right now it is trouble–a lot of it. After the bloody, exhausting wars in Afghanistan and Iraq, Americans have turned inward. In Donald Trump, a major political party is likely to nominate a candidate who questions the basic value of the transatlantic relationship. The E.U., faced with a bewildering number of internal challenges, is fragmenting. On June 23, British voters will go to the polls to determine whether the U.K. will remain in the E.U. A vote to leave would create tremendous turmoil for both the British and E.U. economies. It would remove Washington’s closest E.U. ally from the union. And it could encourage exit referendums in countries like France, Italy and the Netherlands, where public support for a vote is already dangerously high. Unlike Britain, these countries are core members of the euro zone and the Schengen Agreement on open borders. Their exit could derail the entire European project.

But as with so many other issues confronting the U.S. and European governments, these existential risks are not shared across the Atlantic, as during the Cold War. The lack of a common challenge–and a common mission–is reflected in debates over the budget of NATO, the military arm of the transatlantic relationship. Of NATO’s 28 members, only the U.S., Britain, Poland, Greece and Estonia spend at least 2% of GDP on defense, the organization’s baseline expectation, and in absolute terms, the U.S. spends nearly three times as much on defense as the other 27 members combined. Given that NATO’s primary purpose is to defend Europe, not the U.S., it’s not surprising that Americans are left to wonder why a wealthy country like Germany can’t take responsibility for its defense.

Admiral James Stavridis, former NATO Supreme Allied Commander Europe, says the alliance is still worth the cost. “For all its imperfections and challenges, NATO is the best pool of partners the U.S. has in the world: 28 other nations with shared values, high-technology militaries, willingness to participate in global operations like Afghanistan, Iraq and Libya, and deeply intertwined economies,” he says. “All of that will continue to matter deeply.”

But it’s becoming increasingly clear that U.S. and European interests are diverging in basic ways. Europe faces a series of challenges that don’t have the same impact on the U.S. At the top of the list is the flow into Europe of war refugees and economic migrants from Syria, Iraq, Afghanistan, Pakistan, Eritrea and other countries. More than 1.8 million illegal border crossings into Europe were made by migrants in 2015. U.S. Secretary of State John Kerry announced last year that the U.S., home to about 310 million people, would accept about 85,000 refugees from around the world this year but just 10,000 from Syria. Compare that with Germany, a country of 80 million people, which took in about 1.1 million migrants last year. The U.S. simply doesn’t see the migrant crisis–and the causes driving it–as Europe does.

Even on terrorism, a priority for the U.S. and Europe, the two sides are drifting apart. It was striking after the attacks in Paris last November that the French government turned for military support not to NATO, which is treaty-bound to defend members, but to the E.U., activating a rarely cited clause of the Lisbon Treaty that calls for help from other E.U. members. An appeal to NATO would have required a level of cooperation that French officials felt Washington was unlikely to offer quickly, and with Paris bleeding, the French weren’t prepared to wait. And the Orlando attack shows that the biggest terrorist threat the U.S. faces could be from its own citizens–one more way terrorism can isolate.

The U.S. and the E.U. will never fully agree on how best to handle Russia, mainly because Europe is far more vulnerable to the trouble Moscow can start. Even before sanctions were put in place following the start of the Ukraine conflict, U.S. goods exports to Russia in 2013 totaled just $11 billion and U.S. imports from Russia amounted to just $27 billion. Russia was America’s 23rd largest trade partner that year. But Russia is the E.U.’s third biggest trade partner. Germany and most East European countries need Russian energy exports, France needs Russian defense contracts, and Britain needs Russian financial clients. Countries like Italy, Greece and Cyprus have already criticized E.U. sanctions, even if they aren’t ready yet to vote against them. The U.S.-Europe divide on Putin–a divide the Russian President has done his best to widen–will be with us for years to come.

European wavering on Russia reveals something telling: U.S. and European values are diverging. The stark ideological choices imposed by the Cold War order obscured underlying differences in political and economic values both within Western Europe and between Europe and the U.S. Those differences are now impossible to ignore, and the post–Cold War “rise of the rest” has brought an array of competing values into the international system, from Chinese-style state-driven capitalism, to Russia’s aggressive use of energy exports as a political weapon, to protectionism as practiced in India and Brazil.

At the same time, Europe and the U.S. are experiencing individual identity crises. In Europe, the influx of mainly Muslim migrants–and the quotas for how many of them each member must accept–comes at a time of heightened public fear of Muslim terrorists, fueling the anger of European voters already disgusted with unaccountable bureaucrats in Brussels. The result is a surge in support for nationalist, anti-E.U. parties like the Alternative for Deutschland in Germany and the National Front in France. The Sweden Democrats, Austria’s Freedom Party and Switzerland’s People’s Party have all earned double-digit support in recent elections. Europe is also plagued with secessionist pressures that the U.S. doesn’t face. If Britons decide to leave the E.U., Scotland might hold another referendum on its future within the U.K.–and this time could well vote for independence. Catalans are threatening to declare independence from Spain, which has been unable to form a government since an election earlier this year. Europe is divided, vulnerable and insecure.

For many American voters, the unaccountable bureaucrats live in Washington. Trump and Bernie Sanders, populists with little experience or interest in foreign policy, have dominated the headlines, and Trump in particular has attacked what he says are free-riding allies. Both men gripe that Washington absorbs too much of the cost of NATO. Both say recent trade deals have victimized the American worker, and both are opposed to the Transatlantic Trade and Investment Partnership (TTIP), a major trade deal that American and European leaders have been pushing hard, with little traction. This tough political climate has even forced protrade Democrat and likely next President Hillary Clinton to pretend she opposes new trade deals.

It’s no longer clear what Western powers stand for. Do American voters want their government to spend U.S. resources to promote democracy, freedom of speech, rule of law and human rights in other countries? Support for Trump leaves that commitment very much in doubt. Are European leaders committed to these values? Border controls are on the rise throughout Europe. It’s hard to export values that your people may not profess. And if Europe and the U.S. don’t share values, what do they share?

Europe and America are stronger together. But the continued hollowing out of the transatlantic partnership would ensure that dependence on Chinese investment, Russian energy and the cooperation of autocratic governments like Turkey’s will trump political principle. That will prove a loss for a partnership that for all its flaws and limitations has done more than any other in history to promote democracy, freedom of expression and rule of law.

Even if Britons vote to remain in the E.U. and Trump is soundly defeated, U.S. and European leaders have a lot of work to do if they want to save their relationship. First, U.S. and European policymakers must convince skeptical citizens that NATO will enhance security for the world, the West and each member country. That may mean expanding its mission, because if the organization can’t help with urgent issues like the migrant crisis, what is its true purpose? And European leaders have to persuade voters to pay their fair share to support NATO, and counter the criticisms of isolationists like Trump.

On the economic side, U.S. and European leaders should tighten trade and investment ties by committing to the completion of TTIP. The U.S. should work more closely with Europe to combat Chinese restrictions on market access and the theft of Western intellectual property. But they should also join Chinese-led organizations like the Asia Infrastructure Investment Bank to help influence its mission and operations. To restore lost trust from the spying scandals, and extend counterterrorism capacity, Washington should invest in a joint surveillance program with NATO allies. And the U.S. must accept a much larger number of Middle Eastern migrants to help ease the burden on Europe.

From the ashes of World War II, U.S. and European leaders forged an alliance that has done more than any other in history to promote international development and individual liberty. In containing the threat of Soviet expansion, the U.S. helped defend Europe until one famous wall fell. Will Washington be there to help as new walls rise?

Contact us at editors@time.com.

This appears in the June 27, 2016 issue of TIME.

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