The EU has hit Google with its biggest ever fine, imposing a 4.34 billion euro ($5 billion) penalty on the US tech giant for illegally abusing the dominance of its operating system for mobile devices.

Brussels on Wednesday accused Google of using the Android system’s near-stranglehold on smartphones and tablets to promote the use of its own Google search engine and shut out rivals.

The decision, which follows a three-year EU investigation, comes as fears of a transatlantic trade war mount because of President Donald Trump’s decision to impose tariffs on European steel and aluminium exports.

“Google has engaged in illegal practices to cement its dominant market position in internet search,” EU Competition Commissioner Margrethe Vestager said as she announced the huge fine.

The new sanction nearly doubles the previous record EU antitrust fine of 2.4 billion euros, which also targeted Google, in that case for the Silicon Valley titan’s shopping comparison service in 2017.

Denmark’s Vestager ordered Google to “put an effective end to this conduct within 90 days or face penalty payments” of up to five percent of its average daily turnover.

The Google decision comes just one week before European Commission chief Jean-Claude Juncker is due to travel to the United States for crucial talks with US President Donald Trump on the tariffs dispute and other issues.

But Vestager — who was reportedly dubbed by Trump the “tax lady” who “hates the US” after she took on a string of Silicon Valley giants — insisted that she was not anti-American.

“I very much like the US… but the fact is that this (case) has nothing to do with how I feel,” she said.

Google chief Sundar Pichai immediately said the firm would appeal.

“Today’s decision rejects the business model that supports Android, which has created more choice for everyone, not less. We intend to appeal,” Pichai said in a blog post.

Google provides Android free to smartphone manufacturers and generates most of its revenue from selling advertisements that appear along with search results.

The EU says Android is used on around 80 percent of mobile devices, both in Europe and worldwide.