Borussia Dortmund, one of Germany’s most successful soccer clubs, is rooted in the industrial Ruhr region and prides itself on retaining its working-class roots, community engagement and anti-establishment mentality.

That’s why, in the week before one of the biggest games in the club’s history, some Dortmund fans are angry about a sponsorship deal with Rheinmetall, a major German weapons producer. Everyone from club officials to lawmakers have weighed in on the move, which has provoked a debate about the normalization of the military in German society. Still, many fans would rather just focus on Dortmund’s appearance in the showcase game of the European season, the Champions League final on Saturday against Real Madrid.

Dortmund’s three-year partnership with Rheinmetall, announced on Wednesday, includes advertising and marketing rights in Dortmund’s stadium and club grounds but not — crucially for some — a place on the team’s famed black and yellow jerseys. Neither side would confirm the amount of the deal.

Generations of Germans, raised on the postwar idea that “never again” should their nation foment an armed conflict, remain uneasy associating with the defense industry. Unlike in the United States, where professional and college-level sports games often feature soldiers in uniform unfurling American flags and flyovers from fighter jets, at sporting events in Germany outward displays of patriotism and associations with the military are rare.

Some fans would like to keep it that way.

“Borussia Dortmund is a soccer club that has been a standard-bearer for tolerance and social projects,” said Inge Fahle, a retired teacher from Dortmund and a fan of the club since childhood. “A sponsorship with a weapons manufacturer just doesn’t work,” she said.

Hans-Joachim Watzke, Dortmund’s chief executive, said in a statement that the club was “consciously opening ourselves up to a dialogue” by becoming partners with a weapons manufacturer. He said the partnership reflected the role that a company like Rheinmetall has come to play in German society, since the country stepped in to support Ukraine after it was invaded by Russia.