The European Union (EU) remains committed to negotiating over U.S. tariffs but stands ready to defend its interests with "proportionate countermeasures" if necessary, European Commission President Ursula von der Leyen said on Sunday.

Von der Leyen said the tariffs represent a "major turning point" for the United States, according to a readout published by the Commission after her phone call with British Prime Minister Keir Starmer.

"The President expressed her deep concern over the tariffs announced by President Trump on April 2 and the harm they pose to all countries-both through their direct and indirect effects, including on the world's poorest nations," said the readout.

The United States announced a 20-percent tariff on EU imports on Wednesday, prompting concern and pushback from EU member states.