Given the country’s past, cultural resistance to becoming a soldier is high. Can leaders change minds to meet a changing world?

On a rain-soaked morning in late May, dozens of parents gathered on the outskirts of Rüthen, a small town in western Germany, to watch their children race go-karts around a slalom track.

Behind them, flanked by two olive-drab supply trucks, stood a contingent of recruiters from the German Army. In between races, the children climbed around the vehicles, followed by recruiters eagerly gauging their interest in one day joining their ranks.

The children smiled. Many parents did not.

“I think it’s terrible that they advertise to kids,” said Manuel Fleigner, a civil servant. “No one wants their children in the army.”

Germany has long sought to extinguish the militarism that fueled its calamitous history during World War II. But now, facing a growing threat from Russia and the prospect of reduced American support, the government is desperate to change that. It is finding the challenge formidable.

In a survey in June by the Forsa Institute, only 17 percent of Germans said they would defend their country if attacked.

“Younger people don’t really see the purpose of why they should put their lives at risk for Germany,” said Aylin Matlé, a fellow at the German Council on Foreign Relations.

The problem is so acute that Boris Pistorius, the country’s defense minister, is expected later this summer to propose a new form of conscription if the country cannot find enough volunteers.

Germany has committed to significantly expand its military, or Bundeswehr, to 203,000 enlisted people in six years, from about 182,000 today. Many experts say that number is at once too modest, given the looming threat from Russia, and too ambitious.

“We really have a whole new situation, and we really have to talk about what the Bundeswehr will have to do to,” said Lukas Mengelkamp, a political scientist at the University of Hamburg, in northern Germany. “What is the purpose of the Bundeswehr?”

The German military was once half a million strong. But the government trimmed its numbers after the Cold War, then again after 2011, when it ended conscription. The shuttering of bases near German cities further removed the military from public consciousness.

“There are less opportunities for younger people to understand and also to get in touch with serving soldiers, and to get a better understanding of why it is important to have a functioning, defending army,” Ms. Matlé said.

The military is also struggling to compete with the private sector, especially in critical fields like cybersecurity and engineering. It does not help that the military has a reputation for sagging cots and moldy barracks. The government puts the price tag for modernization at $76 billion.

The biggest obstacle is cultural: Picking up a gun is considered anathema to many young Germans.

“It’s not something I could do,” said Jonas Jentsch, a student who was visiting the Bundeswehr’s booth at a sprawling tech trade show in Berlin recently.

The military was showing off its latest cyberwarfare initiatives in the hopes of attracting tech-savvy recruits. Mr. Jentsch said he was impressed.

Still, he added, he was a pacifist.

“It’s not for me,” he said. “I’m against wars.”

To overcome such resistance, the Bundeswehr has sent teams of soldiers to scores of local events like the races in Rüthen. It also uses social media to target potential enlistees.

“We are able to address young people individually and specifically, get them excited about the Bundeswehr,” said Lt. Col. Wolfgang Grenzer, who directs recruiting efforts in Berlin.

In a storefront near his office, Colonel Grenzer showed off one of the military’s many recruiting stations, which it calls career lounges, complete with a model of a cozy, thoroughly modern barracks bed.

Such efforts have paid off: Last year, 51,200 people applied to enlist, up 18.5 percent compared with 2023.

Applications do not always lead to successful enlistments — about a quarter wash out during training — and the Bundeswehr continues to shrink because of an average 20,000 retirements a year.

“Even the most successful recruitment efforts cannot compensate for such a high attrition rate,” a review of the military released in March concluded.

If the recruitment push fails, a potential return to conscription looms.

Reinstating the draft is a divisive issue, including for the parties that form the government. Chancellor Friedrich Merz and his conservative Christian Democrats support the idea. Though Mr. Pistorius, the defense minister, does as well, many in his center-left Social Democratic Party do not.

For now, all 18-year-old men must complete a survey assessing their fitness to serve; the military will approach those who pass with an offer to enlist. Women will be given the option of taking the survey.

It will take time to see the results, time some German leaders fear they cannot afford.

“We don’t have the time right now to try it for two years and then prepare an alternative,” Norbert Röttgen of the Christian Democrats told Die Welt newspaper in May. “The instruments we can resort to if voluntary service fails must be created now.”