European Commission Vice President Teresa Ribera said Donald Trump’s threat to slap tariffs on Spain over its lax defense spending made “little sense” and called for the EU to stand firm against the U.S. president’s “outbursts.”

“Competition in foreign trade is a shared responsibility,” Ribera, a former deputy prime minister of Spain, said in an interview with the Cadena Ser radio network on Monday.

The bloc’s competition chief explained that the EU is a trade bloc and any measures targeting one of its individual members would trigger a collective response.

“I think the EU must be firm, and threatening a member state makes little sense,” she said. “Europe must remain united.”

Ribera lamented that the bonds Brussels and Washington have forged “over decades” are now being tested by “tones, behaviors and outbursts” the bloc never expected would characterize its relationship with a trusted partner like the United States.

“This ‘America First’ thing is worrying, because what it really means is ‘America Alone,’” she said, adding that while the EU is determined to avoid escalating tensions, it also refuses to be pushed around.

“We have to remain firm and defend our principles and our values,” Ribera said. “And we have to work to strengthen our capabilities so that we can reduce our dependence on the fronts we’ve identified over this past year.”