"A tariff of 30% on EU exports would probably have the eurozone economy flirting with, but avoiding, a recession," said Rory Fennessy, senior economist at Oxford Economics. This fits Trump's playbook — he threatened 50% tariffs in May, "only to quickly backtrack following discussions with EU politicians."

The EU says the U.S. is resisting efforts to strike a trade deal and warned of countermeasures if no agreement is reached with U.S. by Aug. 1.

Von der Leyen's decision to resist immediate retaliatory measures points to the European Commission's desire to avoid a spiralling tit-for-tat escalation.