With the conclusion of the North Atlantic Treaty Organization’s 70th anniversary summit in London, it’s fair to say that Donald Trump thinks that most alliance members, starting with France and Canada, are a bunch of ungrateful and unhelpful freeloaders. Fair to say, also, that most of those members see Trump as an erratic, pompous, dangerous simpleton.

There’s no reason they both can’t be right.

The tone of the summit was set several weeks ago, when Emmanuel Macron gave an interview to The Economist, warning of the “brain death” of NATO and wondering whether the alliance’s mutual defense commitments still meant anything. “If the Bashar al-Assad regime decides to retaliate against Turkey, will we commit ourselves under it?” the French president wondered, imagining a scenario in which Ankara could demand that other NATO members play a supportive role in its barbaric adventure in northern Syria.

Macron was widely rebuked for the remarks, most of all by Trump, who this week called them “very disrespectful,” “very, very nasty,” and “insulting to a lot of different forces.”

Yet they were also very true. Trump announced his withdrawal from Syria without bothering to consult France or Britain, both of which had special forces on the ground fighting the Islamic State. It’s Trump, not Macron, who once called NATO “obsolete,” just as it’s Trump who has repeatedly cast doubt on whether the U.S. would defend NATO states from an attack.

Words have consequences. Trump’s domestic political base may think it’s just fine to take the president seriously but not literally. Treaty allies like France can’t be so cavalier. If Macron is now exploring France’s options by talking up the prospect of a European army while talking down the threat from Russia, it’s because that’s where Trump’s wild rhetoric and behavior have led him.

But then we get to the other side of the ledger.

In 2011, Secretary of Defense Robert Gates warned of a “dim if not dismal future” for the alliance if states such as Germany continued to underspend on defense. Nearly eight years later, a German parliamentary report found that fewer than half of the country’s fighter jets, and not one of its six submarines, were combat worthy. The German defense minister recently announced that she does plan to meet NATO targets on military spending, but not until 2031.

To American policymakers of any administration, that sounds like something between a bald insult and a bad joke.

Most other NATO members are no better. Canada, for instance, spends just 1.27% of its gross domestic product on defense (the NATO target is 2%) and cannot meet its obligations to defend North America’s airspace. When Justin Trudeau was overheard at the summit belittling Trump for taking too long with his press conference, the Canadian prime minister sounded to many Americans like a child whining that a working parent had kept him waiting for supper.

All of this means that when Macron and other European leaders muse about creating an autonomous European defense force, they are, as one seasoned Parisian observer put it to me, “playing with cards they don’t have.” Even sizable increases in defense spending wouldn’t fill the gap that an American departure from Europe would leave: Roughly half of European defense spending goes to salaries and pensions, not warfighting capacity.

This is worse than brain death. It’s a philosophical failure, the result of a long-term attenuation in the idea of an Atlantic community — the West — united not only by a shared history or common enemies, but also by a unifying set of ethical and political ideals, and the sense that those ideals entwine our destinies.

That attenuation preceded Trump and Macron, and it has causes that go beyond any two leaders, including fundamental changes in the demographic makeup of both sides of the Atlantic. Even so, it is being accelerated by them. On Trump’s side, through his coarse nationalism, crude transactionalism, and soft spot for strongmen. On Macron’s, from an excess of political opportunism and a dearth of strategic sense. Anti-Americanism will always find a receptive audience with much of the French public. But a Europe without American protection is a continental disaster waiting to happen.

The good news is that an institution as large as NATO can run on autopilot for a long time, certainly beyond either Trump’s or Macron’s tenure of office. At some point, however, real pilots will be needed.

Is there a leader in Europe who can persuasively make the case that NATO isn’t just the cheapest available option for European security, but also the best vehicle for a liberal and democratic identity — and therefore worthy of far greater investment? And is there a leader in the U.S., Democratic or Republican, who can explain that America’s interests must be shaped by our values, and that the ultimate value, the defense of the free world against its common and perennial enemies, is our ultimate interest, too?

Bret Stephens | The New York Times, (Tony Cenicola/The New York Times)

Bret Stephens is an Op-Ed columnist for The New York Times.