European carmakers’ share rally this year might hit a roadblock as a U.S. probe of auto imports raises the potential of new tariffs, with underperforming German manufacturers particularly at risk.

U.S. Commerce Secretary Wilbur Ross submitted a report to President Donald Trump on whether vehicles made abroad pose a national-security risk, according to a statement Sunday. Trump will have 90 days for any response and, if he says he’ll move forward with measures under Department of Commerce recommendations, another 15 days to act.

U.S. government officials haven’t given any insights into the findings. At the Munich Security Conference on Saturday, German Chancellor Angela Merkel rejected the idea that her country’s autos pose a threat to the U.S.

Car producers’ and suppliers’ stocks in Europe have gained in 2019—with the Stoxx 600 automotive index jumping 9.6 percent—amid optimism that the U.S.-Chinese talks will resolve a dispute hampering the industry worldwide. BMW AG and Volkswagen AG have lagged behind as the German companies grapple with weakening demand in their home region and China.

Even with this year’s bounce, the industry still trades at a depressed valuation, with a price-to-earnings ratio of 6.6 that’s by far the lowest among all the sectors in Europe. And the automotive gauge is down 24 percent from a year ago. That’s a little before Trump began tweeting threats to tax German makers’ vehicles, though he’d complained since mid-2017 about the cars’ presence on U.S. streets.

While Trump and European Commission President Jean-Claude Juncker agreed in July to hold off on new tariffs during discussions to resolve an American-European dispute, the U.S. leader’s repeated tweets may indicate he’s primed to add import fees especially targeted at cars from the bloc, according to analysts.

“The risk that tariffs between Europe and the U.S. will come is rather high—I would say slightly more than 50 percent,” Juergen Pieper, an analyst at Frankfurt-based Bankhaus Metzler, said in an email. “Trump seems to have a real problem with German cars.”

The European Union estimated in June that a 25 percent tariff would add about 10,000 euros ($11,300) to the sticker price of a car made in the bloc and sold in the U.S., and would cut American purchases of vehicles and parts in half. The Munich-based IFO Institute’s Center for International Economics calculates that an import fee of that size would cut German car sales to the U.S. by almost 50 percent, or about 17 billion euros, eroding total auto exports by 7.7 percent.

Daimler AG’s Mercedes-Benz brand and BMW, the world’s two biggest makers of luxury cars, and Volkswagen, the largest auto producer globally, have the most at stake from any U.S. trade penalties, even as they’ve reduced the need to bring in vehicles by building American plants. The U.S. is the second-largest market for both Mercedes-Benz Cars and BMW.

France’s Renault SA and PSA Group, the owner of the Peugeot and Citroen marques, don’t sell vehicles in the U.S. PSA shares outperformed the European automotive benchmark in the past 12 months, while among carmakers with a U.S. presence, Daimler has posted the gauge’s worst decline.

Car and component exports from the EU to the U.S. totaled $62.5 billion in 2017 while imports amounted to $17.7 billion, according to a Feb. 15 note by Bernd Weidensteiner, an economist at Commerzbank AG. Germany accounted for $30.5 billion of the outbound figure, though only $8.5 billion of purchases from the U.S.

Even as American imports have declined in recent years as manufacturers established significant U.S. production, the German surplus of $22 billion is “a particular thorn in the side of President Trump,” he said.