Yes, there are indications that the relationship is functioning normally. Donald Trump is planning to attend a NATO summit in May. German Chancellor Angela Merkel and British Prime Minister Theresa May have visited the White House. Trump’s vice president and defense secretary have traveled to Brussels to assure nervous NATO members that their boss remains committed to the military alliance so long as European countries increase their defense spending.

Yet signs of distress in transatlantic ties are arguably more evident. Last week’s meeting between Merkel and Trump was quickly marred by sparring between the U.S. and German governments over Germany’s financial contributions to NATO. The Trump administration was simultaneously quarreling with Britain’s government after airing unverified allegations by a Fox News commentator that Barack Obama had conspired with a British intelligence agency to spy on the Trump campaign. (The U.K. intelligence agency took the extraordinary step of denying those claims publicly, with a spokesman calling them “utterly ridiculous.”) During a Group of 20 meeting in Germany over the weekend, U.S. Treasury Secretary Steven Mnuchin defied Asian and European finance ministers and central bankers by opposing pro-free trade language in the group’s joint statement. This week, Japanese Prime Minister Shinzo Abe is in Brussels to advance a long-stalled trade deal with the European Union, as the EU seeks to position itself as an alternative free-trade partner to Trump’s protectionist United States. (Trump recently withdrew from a massive trade agreement with Asian nations, and has promised to renegotiate the U.S. trade accord with Mexico and Canada.) Several European leaders, citing Trump’s repeated questioning of NATO’s value and praise of Britain’s exit from the European Union, have characterized the American president as a threat to the decades-old project of unifying Europe. There are even murmurs among some European officials about establishing an EU nuclear-weapons program if the region loses American military protection.

These trends were foreseen, though not inevitable. Reflecting on America’s long history of opposing alliances and passionate embrace of them during World War II and the Cold War, the political scientist Rajan Menon once observed that alliances “reflect specific circumstances, and when these circumstances change, the shared practical interests that are vital to the health and life span of alliances begin to erode.” Writing in 2003, he predicted that elaborate Cold War-era alliances would soon be replaced by “agile, shifting coalitions forged for specific purposes.” He noted that today’s grand causes, including the war on terrorism and the promotion of democracy, “will not become new unifying objectives; they are too diffuse and amorphous to concentrate minds and ensure consensus.” He argued that NATO in particular “is endangered because the disintegration of the Soviet Union has robbed it of a clear and common enemy and an unambiguous purpose.”