When German reunification happened in 1990, this fortunate turn of events corresponded strongly with the way the United States viewed the world. The right side had won, history had taken a good turn, and freedom had prevailed after a long standoff with the forces of oppression.

For Germans, the picture was less clear. Even though most Germans were elated and couldn’t resist the contagious optimism of the day, many felt ambiguous about reunification. Do we as Germans deserve this? Are we ready to be one again? Can this be economically managed? What will our neighbors think? Germany’s broken national identity very much mirrored the attitude Germans brought to this unique moment in their nation’s history.

Things have changed since then. Germany has gone through all the emotional, cultural, economic, and political highs and lows of reunification. Economic crisis was followed by a boom. The country’s role in both NATO and the EU has altered. And as a consequence, Germany’s relationship with the United States has evolved. But how so?

A Promise Unfulfilled

For America, the reunified Germany is a promise at least partly unfulfilled. In 1990, expectations in Washington were very high—perhaps naively so—that Germany, almost in an instant, would become a normal nation, easily shedding its erstwhile restrictions and embracing a new international leadership role with natural confidence. This hope was famously expressed when the former U.S. president George H. W. Bush invited Germany to be America’s “partner in leadership.”

Some of this has become true. The reunified Germany, after much soul-searching and some missteps, has taken on a role in international and European affairs that would have been unthinkable in 1989.

But from an American perspective, one important thing has not changed enough: Germany’s reluctance to also be a military power. To be fair, Germany has moved substantially out of its comfort zone in Kosovo, Afghanistan, and, more recently, Iraq—as well as with the reassurance measures NATO has taken on its eastern flank since the Russian annexation of Crimea in March 2014.

And yet, Americans feel strongly about the fact that Germany needs to do more. For Washington, Germany is the key player when it comes to moving Europeans to spend more on defense. Germany’s reluctance to conduct expeditionary operations is less and less accepted as the outflow of history and a special German mentality. Whether outspoken or not, Americans expect Germany to play a role in stabilizing the globe that is commensurate with the country’s global economic weight. As long as this is not the case, Americans will deem German reunification to be an incomplete process.

Europe Done and Dusted?

The reunification of Germany, alongside the collapse of the Soviet Union, had one important impact on U.S. foreign policymakers. They believed that Europe was a closed case, geopolitically. This aligned very well with the German sentiment that saw the country as part of a postmodern peace project called the European Union, which, in turn, fed the idea that the ugly parts of politics were not for Germans. This created a mutually reinforcing complacency regarding European security affairs in both Berlin and Washington.

Now, with Crimea annexed, Ukraine at war, mass migration, and the wider European neighborhood riddled with conflict and instability, both Europeans and Americans have to relearn that the old world is less of a done deal than expected.

This will mean different things for both sides. For America, this is about keeping alive the credibility of its NATO-administered security strategy for Europe while pushing Europeans to shoulder more of their own defense burden.

For Germany, this will mean finding a leadership role that fits the country’s size without creating nervousness and a fear of hegemony both at home and in Europe. In more concrete terms, this means that Germany will have to become, against all instincts, a much more integral part of NATO’s hard Article 5 mutual defense guarantee than it used to be.

The haggling over how to keep Europe safe in light of increased geopolitical tension will determine the German-U.S. relationship for some time to come.

Obnoxious Ally?

With grown importance and self-confidence on Germany’s side, there is also a growing risk of the United States and Germany getting into serious disagreements on big political questions.

Former U.S. president George W. Bush experienced this when his relationship with the then German chancellor Gerhard Schröder fell apart over the 2003 U.S.-led invasion of Iraq, which Germany vehemently opposed. Bush’s successor, Barack Obama, found out that today’s chancellor, Angela Merkel—based on very different economic instincts and experiences—had ideas about how to resolve the euro crisis that diverged greatly from his own.

Future Republican administrations might discover that Germany, despite its current robust posture vis-à-vis Russia, will always try to steer a less antagonistic course with Moscow than they find desirable. Similar clashes could occur on issues such as China, climate change, NATO enlargement, financial regulations, and trade. In such cases, it is likely that Germany will be a tougher and more assertive counterpart. This is the price America pays for having helped Germany reunify. It remains a small price for a historic achievement.

Germans, in turn, must be careful that their newly found confidence does not enter an unholy alliance with the temptation to go it alone—or even with anti-Americanism, which is a sentiment all too present just beneath the surface.

Westbindung—Germany’s firm embedding into the family of Western nations, and thus its close relationship with the United States—will remain a question of political destiny for Germans, for Europe as a whole, and for America as a European power. This truth remains unchanged even a quarter century after reunification.

This essay was originally published by the American Institute for Contemporary German Studies.