James Kirchick, a visiting fellow at the Center on the United States and Europe at the Brookings Institution, is the author of “The End of Europe: Dictators, Demagogues, and the Coming Dark Age.”

BERLIN — The North Atlantic Treaty Organization was founded, according to its first secretary general, Lord Hastings Ismay, “to keep the Soviet Union out, the Americans in, and the Germans down.” Seventy years ago this Thursday, as the Soviet Union was violently propping up puppet governments across Eastern Europe, Western leaders signed a mutual defense pact establishing NATO as a bulwark against communism.

Well, the Russians are rattling sabers again — and the United States is still needed both to contain an expansionist Moscow and dampen strategic competition among NATO’s European member states. But what about that third member of Ismay’s equation? Germany today is a sterling exemplar of liberal democracy — and a shaky alliance partner.

It is not just President Trump, perpetually complaining about Berlin’s paltry defense expenditures, who thinks Germany needs to assume greater responsibility. Eight years ago, Poland’s then-Foreign Minister Radek Sikorski delivered a widely noted speech in Berlin in which he referred to Germany as Europe’s “indispensable nation” and said that “I fear German power less than I am beginning to fear German inactivity.” These words were momentous because of the difficult history between the two countries. World War II began with the German invasion of Poland, and millions of Poles were murdered in that conflict.

But now with Vladimir Putin’s Russia threatening the European security order and Germany a vital member of the liberal democratic club, it is not German aggression that anyone seriously fears but its opposite: passivity. At the 2014 NATO summit, Germany joined the rest of its allies in agreeing to spend 2 percent of its gross domestic product on defense by 2024. Five years later, it is nowhere near accomplishing that goal. Last month, the country’s Social Democratic finance minister announced that defense spending will hit 1.25 percent of GDP by 2023. While Chancellor Angela Merkel insists that the number will be closer to 1.5 percent, that is still well short of what Germany promised.

Germany’s underinvestment in defense has long been a topic of concern among NATO watchers, but it became particularly sensitive once Trump began attacking the country repeatedly on the campaign trail. More than two years into his turbulent administration, the issue has helped bring U.S.-German relations to their worst point since the Iraq War, when Social Democratic Chancellor Gerhard Schröder was reelected after running an explicitly anti-American campaign. U.S. Ambassador to Germany Richard A. Grenell, who is close to Trump, has repeatedly and publicly criticized Germany for not meeting the 2 percent threshold. Last week, foreign policy scholar Jakub Grygiel, until last year a member of the Trump State Department policy planning staff, wrote an article excoriating Germany as “a dangerous pacifist.”

In some ways, the 2 percent hurdle is an arbitrary measure of a country’s commitment to mutual defense; Germans have frequently suggested to me that their generous humanitarian aid budget and absorption of more than a million refugees ought to count toward their NATO spending target. But although there may be many metrics for calculating a nation’s contribution to the alliance, the German shortfall doesn’t even begin to capture the dismal condition of its armed forces. A report last year found that only a third of Germany’s military assets — including its jets, transport helicopters and navy frigates — are even operational.

As Europe’s richest and most populous nation, Germany can and should do more. In light of its massive budget surpluses, the decision not to meet the 2 percent goal — and it is a decision, not an inevitability — appears spiteful, almost designed to annoy Trump. Some German politicians are playing semantics over the wording of the 2014 NATO declaration, insisting that the “aim to move towards the 2% guideline” is not an explicit endorsement but a mere suggestion.

Narrow-minded and negligent as Berlin’s scrimping on defense may be, Trump is partly to blame for this situation. His constant berating of allies, rhetorical undermining of NATO and all-around indecency have rendered the issue of defense spending politically toxic in Germany, where, given the country’s history, it is already a political millstone. Leaders here are understandably hesitant to make the case for increased military spending so as not to be associated with one of the most unpopular American presidents in history.

Yet Germans need to get past their intense personal dislike of this particular White House occupant and realize that enhancing their defense capabilities is in their own best interest. That they are unable to is evidence of a profound political and strategic immaturity. Rebuilt by the United States after World War II and protected by it ever since, Germany is, according to one Berlin political analyst, like a “spoiled child living in its parents’ house.” For all their complaining, 65 percent of Germans still believe that the United States would fulfill its NATO commitment by using military force to defend an ally threatened by Russia, while only 40 percent think their own country should. Consider the current transatlantic tensions a belated, if inevitable, form of growing pains.

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