US President Donald Trump warned of fresh tariffs on the European Union (EU) after Brussels imposed a €2.95 billion ($3.47 billion) fine on Google for antitrust violations.

On Friday, the European Commission announced the penalty, ruling that Google abused its dominance in the online advertising market by favoring its own ad exchange services over competitors. The decision marks the fourth major fine against Google in a decade-long battle with EU regulators.

“Europe today ‘hit’ another great American company, Google, with a $3.5 billion dollar fine, effectively taking money that would otherwise go to American investments and jobs… Very unfair, and the American taxpayer will not stand for it!” Trump posted on Truth Social.

The US President said his administration “will not allow these discriminatory actions to stand” and warned he would launch a Section 301 investigation — a trade tool often used to justify retaliatory tariffs. “I will be forced to start a Section 301 proceeding to nullify the unfair penalties being charged to these taxpaying American companies,” Trump said.

The European Commission also ordered Google to cease its anti-competitive practices. EU antitrust chief Teresa Ribera said the ruling “shows that Google abused its dominant position in ad tech, harming publishers, advertisers and consumers.”

Google has vowed to appeal the decision, calling the fine “unjustified.”

Trump, however, noted that Google has already paid $13 billion in past EU penalties, totaling $16.5 billion. “How crazy is that? The European Union must stop this practice against American companies immediately!” he said.

The dispute adds pressure to already fragile US-EU trade relations. A new transatlantic trade framework was approved earlier this year, but many European leaders remain skeptical about its long-term future.