Europe’s major car exporters remain uncertain over the U.S. tariff regime despite a trade deal reached last month, shipping giant Wallenius Wilhelmsen said on Tuesday.

The company, which operates one of the world’s largest car-carrier fleets, said the lack of clarity is affecting trade flows for manufacturers such as BMW, Mercedes-Benz and Volvo Cars.

The U.S. and European Union agreed in late July to set import tariffs on most European goods, including cars, at 15%.

This followed a sharp increase earlier this year when U.S. President Donald Trump raised the rate to 27.5%.

However, the reduced 15% tariff for vehicles has yet to take effect. The absence of an executive order from Trump to lower the auto tariff has left the industry bracing for potential last-minute changes.

“So far, we actually do not know exactly what the tariff level will be. Our customers do not know either, so it is too early to say what they'll do,” Wallenius CEO Lasse Kristoffersen said after the company’s quarterly results.

Kristoffersen said that earlier in the year, carmakers accelerated shipments to the U.S. to beat the higher 27.5% levy.

By contrast, at the start of the second quarter, shipments slowed as exporters held back, only picking up again later in the quarter.

“We saw that they held more back in the start of the second quarter but that volumes increased throughout the quarter,” he said.