The relationship between the world's major powers is being unpredictably transformed. To be clear, it's not just that the United States is seeking a new balance of power with Russia or China. If you look close enough, you can see cracks in the transatlantic Western alliance. And there seems to be no way to hide them anymore.

Britain's decision to leave the European Union and Donald Trump's surprise victory in last year's U.S. presidential election meant that Europe could not longer put off having "the talk" about its "destiny." Efforts to mitigate the concerns of European leaders, including last week's NATO meeting in Brussels and the G7 summit in Taormina, Italy, proved futile. Quite the contrary, it would appear that the Europeans started taking the issues of defense and security more seriously.

To be clear, President Trump delivered a more diplomatic speech in Brussels than expected and refrained from saying that NATO was "obsolete," as he had suggested on the campaign trail last year. He did, however, make references to his campaign slogan, "America First," by noting that 23 out of the alliance's 28 members did not meet their financial obligations, which, he argued, was "not fair to the people and taxpayers of the United States."

It goes without saying that his criticism was directed, among others, at Germany, which spends just 1.2 percent of its GDP on defense even though the country's trade surplus amounted to $295 billion last year. At a campaign event in Munich on Sunday, German Chancellor Angela Merkel responded to Mr. Trump's comments by saying, "The times in which we could completely depend on others are over," and calling on Europeans to "take our destiny into our own hands." The ever-diplomatic German leader, who carefully refrained from making controversial statements about Turkey in recent years despite bilateral tensions, suddenly took a jab at Britain and the United States, which is why Mrs. Merkel's comments were important.

Unless the German chancellor wanted to make Europeanism the centerpiece of her re-election campaign, there is no reason to believe that she was just repeating the old line that it was important for Europeans to have a common identity. To be clear, nor was she engaging in a philosophical debate about the meaning of Europe. Instead, Mrs. Merkel made it clear that she had serious concerns about the continent's strategic future. Unable to create a common European army, EU leaders face serious challenges in the area of defense and security. Moreover, it is important to keep in mind that the Soviet Union's collapse and German reunification made it possible for Germany to dominate European economy and politics, which is what the German chancellor really wanted to address. By forcing Mrs. Merkel to talk about the future of Europe, the U.S. president raised a thinly-veiled objection to German domination of the continent and presented Berlin with a serious challenge: to speak for Germans and Europeans at the same time.

Although Brexit had raised questions about the European Union's future, the election of the pro-European Emmanuel Macron in France signals that Paris and Berlin will continue to lead the continent. However, provided that the dream of a European army remains elusive, the only viable alternative could be the least desirable: By ignoring post-World War II restrictions on its military, Germany could create an impressive fighting force – provided that the Americans are willing to let their European order crumble and Europe become unmistakably German.

In other words, the sticking point is that the European Union needs Germany to lead in the absence of Britain. But a number of countries, including France and Italy, would be deeply frustrated if the Germans try and take the lead. Although Mrs. Merkel argues that "Germany can only do well if Europe is doing well" in an effort to mitigate European concerns over Berlin's domination, it won't be easy to reconcile the German interests with Europe's destiny.