WASHINGTON (AP) — The United States will open a formal investigation into the European Union’s trade practices, President Donald Trump said on Friday, claiming the bloc has unfairly levied billions of dollars of fines against Google, Apple and other U.S. tech giants.

The Republican president made the announcement a day after the EU hit Google with a fine of 890 million euros, or $1 billion, after it said the technology behemoth broke digital antitrust regulations by setting up Google Play and its ubiquitous search engine to corral consumers toward its own services and apps to the detriment of competitors.

In a lengthy post on social media, Trump said he has warned the EU about its practice of fining U.S. tech companies. He named Google, Apple, Meta, Amazon and others.

“The United States of America is not a ‘PIGGYBANK’ for Europe, nor will we allow it to be!,” Trump said, adding that his post should serve as notice of an immediate trade investigation “into the practice of ‘ROBBING’ American Companies and, in turn, the American Taxpayer.”

“The European Union will pay a very big price for this illegal and highly unethical conduct, which I have consistently warned them about,” he said.

In the post, Trump asserted that the penalties against the companies “will be entirely reversed” and predicted “a substantial TARIFF” would be placed on the EU “at the earliest possible moment.”

“Stay tuned!” he said.

Trump’s move comes a day after the White House announced double-digit tariffs on imports from more than 60 countries, accusing them of inadequately enforcing bans on goods produced by forced labor. The new tariffs replace temporary 10% worldwide import taxes that Trump imposed after the Supreme Court struck down his biggest tariffs.

The new tariffs are being implemented using Section 301 of the Trade Act of 1974, which permits the president to impose import taxes and other sanctions against countries found to engage in “unjustifiable,” “unreasonable” or “discriminatory” trade practices.

Darlene Superville And Collin Binkley, The Associated Press