The announcement from the Office of the United States Trade Representative ended a monthslong investigation into the French tax, which hits companies like Facebook and Google even though they have little physical presence in France. The investigation concluded that the tax “discriminates against U.S. companies, is inconsistent with prevailing principles of international tax policy and is unusually burdensome for affected U.S. companies.”

It recommended tariffs as high as 100 percent on certain French imports valued at $2.4 billion, including cheese, wine and handbags.

President Trump, in London on Tuesday for a NATO summit meeting, said the finding was justified. “They’re starting to tax other people’s products,” he said, according to a pool report. “So therefore we go and tax them.”

France’s economy and finance minister, Bruno Le Maire, on Tuesday denounced the tariff threat as “unacceptable” and said that Europe would come ahead with a “strong response,” without elaborating on possible retaliatory measures.