Perhaps no item on President-elect Donald Trump's foreign-policy agenda is as unclear as his new administration's approach to the American relationship with Europe. There are some obvious reasons for this. At various moments in the campaign, he appeared to call into question the Atlanticist consensus over security and economic policy supported by U.S. administrations and European governments for nearly seventy years. Among other things, he questioned the relevance of the NATO alliance and his commitment to abiding by the Article Five obligation to come to the aid of allies under attack. At the same time, he underscored his disdain for the European Union by openly supporting Brexit while also singling out Chancellor Angela Merkel for her open-door policy towards migrants from conflicts in the Middle East. Meanwhile, European governments are unnerved by President-elect Trump's call for scuttling the Iran deal and walking away from the Paris agreement on climate change.
Prospects for U.S.-Europe relations during the Trump era, at least at this point, do not look good. The question that many Americans (including some Trump supporters) might ask is: does it matter? Europe seems to confront a multiplicity of crises, ranging from internal challenges, such as low economic growth and rising populism, to external threats, including Russian aggression and Middle East terrorism, that seem to be sapping the continent's political resolve and global position. So why, then, should a new Trump administration waste energy and resources on working out common strategies with the Europeans?
From a historical perspective, the answer is clear. In both the Cold War and the post-Cold War eras, U.S. international primacy has flowed, at least in part, from America's security partnership with Europe. In the 1980s, an important element of the Reagan administration's military buildup was strengthening NATO. Then, following the collapse of the Berlin Wall, the United States, working closely with Britain, France and West Germany, was able to achieve the peaceful reunification of Germany in negotiations with Russia. More recently, U.S. and European collaboration on Ukraine-related sanctions and in fighting the Islamic State have not only augmented American leverage but conferred political legitimacy on these policies.
This is not to suggest that all is well within the alliance, particularly as far as burden sharing is concerned. Even Barack Obama has complained about the "free-rider" problem within NATO. And on the campaign trail, Trump repeatedly called for higher European defense spending. But this is a topic where Trump can already claim some credit: expecting new...