It has taken nearly a month, but workers striking against Tesla in Sweden have finally drawn a response from the company’s famously anti-union boss. “This is insane,” CEO Elon Musk said Thursday on X, the platform formerly known as Twitter that he owns. Musk was responding to news that Swedish postal workers are refusing to deliver Tesla license plates, joining a wave of action in sympathy with mechanics who stopped servicing Tesla cars late last month. About 130 mechanics began their ongoing strike in October after their employer, a Tesla subsidiary in Sweden, announced that it would not recognize their labor union, according to Expressen, a CNN affiliate. The industrial action soon spread to dockworkers who started blocking deliveries of Tesla cars at the country’s ports, to electricians who stopped maintenance work for the carmaker, and other workers in Sweden, Expressen reported. “This is about good wages, good pensions and good insurance for all our members who work at Tesla,” Sweden’s IF Metall union, which called the original strike, said on its website. “We have been negotiating with Tesla for a long time. They have refused to sign a collective (bargaining) agreement and violate basic principles in the Swedish labor market.” The country’s workforce is heavily unionized, with around nine out of 10 workers covered by collective agreements. But unionizing at Tesla has proven difficult. At least three attempts by its US workers to organize have failed, mainly as a consequence of aggressive tactics by the company and weak protections for labor in the United States. The National Labor Relations Board, a US federal agency, has repeatedly called out Tesla and Musk for illegal or improper anti-union activities, such as interrogating employees, and disciplining or otherwise discriminating against workers because they support unions. This year the carmaker fired more than 30 supporters of a nascent union at its facility in Buffalo, New York, just days after the organizing effort was announced. Musk, the world’s richest man, has also been vocal about his opposition to unions and caused the ire of the labor relations agency when it directed him to delete a 2018 tweet that hinted Tesla employees would lose their stock options if they formed a union. Still, the strikes by Swedish workers may embolden Tesla’s employees in Germany, where it has a large plant manufacturing electric vehicles and battery cells. German unions have pressured the company to implement a collective bargaining agreement for its 11,000 workers at the factory near Berlin, according to Reuters. IG Metall, a powerful German Union, says Tesla pays its workers less than other carmakers in Germany and gets rid of employees who are sick too often. More than 1,000 workers at the factory joined the union during a day of protest last month. Earlier this year, Tesla lodged an application to double the production capacity of the plant — located about 30 kilometers (18 miles) from the German capital — to 1 million EVs. If the expansion happens, the factory will overtake Volkswagen’s sprawling plant in the German city of Wolfsburg, stealing its crown as Europe’s biggest car factory.