Since the US president unleashed tariffs targeting steel and aluminium, cars, and finally a majority of imports from the European Union, the bloc has insisted it seeks a mutually beneficial agreement with Washington.

But now in her strongest comments yet, von der Leyen indicated that she was ready to step up her threats of retaliation and target American services if negotiations fall short.

"There's a wide range of countermeasures ," she said, if talks yielded no result.

"An example is you could put a levy on the advertising revenues of digital services" applying across the bloc, said von der Leyen, who raised the use of a new trade weapon called the anti-coercion instrument, according to the FT.

Dubbed a "bazooka", the weapon has never been used but empowers the EU to target services and could limit American companies' access to public procurement contracts in Europe.

Among the grievances fueling its tariff campaign against Europe, the US administration has complained about so-called non-tariff barriers that it argues unfairly hamper American exports.

In particular officials have taken umbrage at the bloc's value-added taxes (VAT) and stringent rules on tech, the Digital Markets Act and the Digital Services Act, which regulate tech competition and content moderation online respectively.

The tech laws were "untouchable", von der Leyen told the newspaper, and said the EU would not be open to negotiate on VAT, which applies to both domestic and imported goods.

While the interview laid down a series of red lines, von der Leyen has sent strong signals she wants the talks to be successful.

She announced earlier on Thursday that the bloc would put planned tariffs on US goods on hold "to give negotiations a chance" after Trump's U-turn on massive new duties, despite the fact that his previous levies on metals and cars remain in force, as does a baseline 10 percent tariff on all goods.