United States President Donald Trump has threatened the European Union with steep tariffs and a new trade investigation, saying that the bloc “will pay a very big price” after Brussels fined Google $1bn over antitrust violations .

Trump called penalties against Google and other US tech firms “highly unethical”, saying on Friday that the US “is not a ‘PIGGYBANK’ for Europe”.

“This illegal and highly discriminatory practice started at these high levels during the first year of the Sleepy Joe Biden Administration, but it’s not going to continue during the Trump Administration,” he wrote in a social media post.

The European Commission had imposed the fine on Thursday, ruling that Google had breached the bloc’s Digital Markets Act by favouring its own services in search results and restricting app developers from directing users elsewhere.

The penalty adds renewed strain to US-EU relations at a moment when trade tensions between Washington and Brussels had appeared to ease.

Regulators said Google gave preferential placement to its own shopping, travel and other services over rival offerings, and blocked app developers from steering customers towards deals outside its Play Store.

The EU Commission split the penalty roughly in half between the two breaches, giving Google 60 days to change its practices or face periodic fines of up to 5 percent of its average daily turnover.

Teresa Ribera, the commission’s executive vice president overseeing competition policy, on Thursday called the action “decisive yet balanced”, arguing that products should succeed on merit rather than ownership.

Kent Walker, a Google executive, described the ruling as “product degradation” driven by a small number of complainants, insisting that regulation should improve products rather than weaken them.

The EU has fined Google repeatedly since 2017, including a $4.5bn penalty over its Android operating system, upheld on appeal this month, and a $3.4bn fine last year targeting its advertising business.

The latest penalty also reignites friction with Washington.

Jamieson Greer, the US trade representative, warned this week that Brussels’s approach towards American tech firms risks unravelling a trade deal struck in Turnberry, Scotland, last year that capped US tariffs on European goods.

EU officials have pushed back, insisting they answer to their own laws rather than outside pressure.

Trump threatened to launch a probe under Section 301, a US tool for probing unfair trade practices, but the move could take months to produce results, though tariffs could follow far sooner.