Europe’s pharmaceutical lobby group has criticized Donald Trump’s decision to impose up to 100 percent tariff on drugs coming from overseas, calling it the “worst of all worlds.”

But it’s not clear what rate products from the EU would face.

The U.S. president announced Thursday evening that brand-name or patented pharmaceutical products will be subject to tariffs from Oct. 1 — unless a drugmaker is building a manufacturing plant in the United States.

“‘IS BUILDING’ will be defined as, ‘breaking ground’ and/or ‘under construction.’ There will, therefore, be no Tariff on these Pharmaceutical Products if construction has started,” Trump wrote on Truth Social.

“Tariffs increase costs, disrupt supply chains and prevent patients from getting life-saving treatments,” said Nathalie Moll, director general of the European Federation of Pharmaceutical Industries and Associations (EFPIA), whose members include Novo Nordisk, Pfizer and AstraZeneca.

Products from the EU should in theory only be subject to a maximum 15 percent tariff, after the European Commission negotiated a knocked-down rate in its deal with Washington in July.

Trump’s latest post raises questions about how binding the EU-U.S. trade deal is, which limits branded medicines’ tariffs. The deal agreed in July between the pair also sees cheaper generic medicines exempt from the tariffs.

Olof Gill, deputy chief spokesperson for the European Commission said the EU does not expect its industry to pay more than 15 percent.

“This clear all-inclusive 15% tariff ceiling for EU exports represents an insurance policy that no higher tariffs will emerge for European economic operators,” Gill said. “The EU is the only trade partner to achieve this outcome with the US.”

Ireland’s Trade Minister Simon Harris said the EU-U.S. trade deal made it “absolutely clear” that a tariff applied to branded drugs from the EU would be capped at 15 percent.

The post also raises the question about whether the United States could tariff individual companies in the same sector at different rates.

Although the Trump administration has signaled time and again that it doesn’t pay much heed to rules-based trade, governments can’t simply slap a higher “regular” tariff on one foreign company and a lower one on another under World Trade Organization rules. Duties are usually applied uniformly to all exporters from a given country, or target a specific product altogether — such as steel or medicines — in case of dumping or unfair subsidies.

Moll said that “tariffs on medicines, however excessive, would create the worst of all worlds.”

She urged Brussels to reopen negotiations with Washington, saying they should discuss “how the EU can improve its support towards the cost of global research and development in a way that doesn’t harm patients in the EU and the US.”

“The EU and US continue engaging towards implementing the Joint Statement commitments, while exploring further areas for tariff exemptions as well as wider cooperation,” Gill said.

Earlier this week, an official from the Commission’s DG TRADE also said that the EU would continue to push for exemptions to the U.S. tariffs for pharmaceutical and medtech products.

Several companies have already said they will increase investment by building new plants in the U.S. in recent months, with Johnson & Johnson and Eli Lilly among those all committing to spend in the country.

The story has been updated with Ireland’s position.