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.