Musk’s tweet was promoting another tweet from Naomi Seibt a German climate change denier who rose to prominence as the anti-Greta Thunberg. Seibt has also promoted conspiracy theories and been accused of being antisemitic, according to the Guardian, a claim she denies.

It was not the first online intervention by Elon Musk, the entrepreneur and adviser to Donald Trump, on behalf of once-fringe anti-immigrant parties in Europe.