Tesla sued Sweden’s postal agency after mail workers in the country refused to deliver license plates in solidarity with striking service autoworkers.

As CNBC reports, the company calls postal workers’ refusal to deliver license plates a “discriminatory attack” and says that the Swedish government has a “constitutional obligation” to get plates to vehicle owners.

About 130 workers at seven Tesla repair shops in Sweden have walked out in the past month as ordered by their labor union, IF Metall, the largest union for manufacturer workers in the country. Tesla has refused to negotiate a collective bargaining agreement with the striking workers. Other unions have thrown in their support, including dock workers who won’t take Tesla vehicles off cargo ships.

On November 20th, postal workers joined the escalating strike in solidarity by refusing to deliver Tesla’s mail. The automaker’s lawsuit aims to change a strict policy with Sweden’s Transport Agency where license plates must go through the state-run postal company called PostNord. The agency won’t allow Tesla to pick up plates directly or via other avenues.

Tesla has been accused of resisting unionization in facilities in the US, including allegedly firing pro-union workers as retaliation for attempting to organize in Buffalo, New York, and suppressing employees from discussing pay in Orlando, Florida.