President Donald Trump listens during a cabinet meeting at the White House in Washington on July 18, 2018. REUTERS/Leah Millis (Leah Millis/Reuters)

President Trump on Thursday attacked the European Union over its decision to fine Google $5 billion for harming its competitors, tweeting that the incident proved the regional bloc has “taken advantage of the U.S., but not for long!”

To Trump, the fine appeared to serve as the latest evidence of Europe’s exploitation of the United States on a variety of matters, including trade and other nations’ contributions to defense spending, and it came a day after he threatened “tremendous retribution,” particularly on European-made cars if the E.U. doesn’t change its policies.

European leaders, however, showed no sign of backing down Thursday — with one official pledging in Brussels that they could adopt their own “rebalancing measures” if the U.S government proceeds fresh new auto tariffs.

On Wednesday, the European Union found that Google harmed consumers and competitors for pushing its search and web-browsing tools on the makers of Android-equipped mobile devices. The fine marked the second time in about a year that regional regulators have needled Google for its business practices.

In doing so, Margrethe Vestager, the E.U.'s top competition official, stressed the fine was proportional to Google’s revenue and not motivated by recent transatlantic disputes. Her investigation of the search giant, in fact, predates Trump’s arrival at the White House.

“I very much like the U.S.,” Vestager told reporters at a press conference Wednesday, adding: “We have to protect consumers and competition . . . this is what we do. It has been done before, we will continue to do it, no matter the political context.”

The E.U.’s penalty still stood in stark contrast with the United States, where federal antitrust regulators previously investigated Google’s search and advertising businesses but concluded their probe in 2013 without bringing major penalties against the tech giant. Since then, Democrats and Republicans alike have mused whether the Federal Trade Commission, an independent agency, should open a new investigation into Google’s sprawling footprint.

“The FTC should end its decade of inaction and deference, and confront the mounting evidence that Google’s business practices have stifled robust competition in a market that is critical to our economy and society,” said Democratic Sen. Richard Blumenthal in a statement Wednesday. "Europe should not be alone setting the agenda.”

A spokeswoman for the European Commission declined to comment on Trump’s tweet. But the aide added that Jean-Claude Juncker’s trip to Washington D.C on July 25 will be a “good opportunity” for the commission’s president to discuss all matters related to the tense transatlantic relations.

Meanwhile, the European Union’s trade commissioner, Cecilia Malmström, reiterated Thursday that the response to Trump’s tariffs will be strong, as the bloc looks to preserve the essence of the postwar transatlantic relationship.

“The EU does not want to escalate the situation,” she said. “However, we have had no choice but to respond. We are not prepared to walk away from what we built together, to let the global order fade away like an old memory. So we have taken action in a way that is reasonable, proportionate and in accordance with international rules.”

As he grapples with Europe, Trump also has struggled to befriend the tech industry: He’s attacked companies, such as Apple and Amazon.com, while the leaders of those companies and their peers have blasted the president in return for his approach to issues, such as immigration and climate change. (Amazon chief executive Jeff Bezos is the owner of The Washington Post.)

But Trump’s new broadside against the E.U. for investigating Google may elate many of its digital counterparts, which have struggled to escape the scrutiny -- and strong punishments -- of Silicon Valley’s skeptics across the Atlantic.

In recent years, Vestager has penalized Apple for failing to pay its taxes and fined Facebook for a series of privacy mishaps, including a punishment last week from the United Kingdom for the social giant’s entanglement with Cambridge Analytica. In May, the European Union also began implementing tough, new rules on how tech firms can collect, store and monetize users' data, a privacy regime that could result in massive fines for offending companies.

And Vestager on Wednesday even promised further scrutiny of Google, stressing as she announced her $5 billion fine — a new record for the E.U. — that regulators are probing other elements of the company’s search and advertising business. Google has already said it would appeal her Android decision.

Writer Quentin Aries contributed to this report.