The US-European tariff conflict is jeopardising transatlantic business worth $9.5 trillion annually, the American Chamber of Commerce to the EU warned on Monday.
AmCham EU, whose more than 160 members include Apple, ExxonMobil and Visa, showed in its annual Transatlantic Economy report a deepening relationship hitting records in 2024, such as goods and services trade of $2 trillion.
In the past week, Washington has imposed tariffs on steel and aluminium, the EU has set out plans for retaliation and President Donald Trump has threatened 200% tariffs on EU wine and spirits.
Trump has railed against the US goods trade deficit with the EU, although in services there is a US surplus, and urged manufacturers to produce in America.
AmCham said trade is only part of transatlantic commercial activity and that the real benchmark was investment.
"Contrary to conventional wisdom, most US and European investments flow to each other, rather than to lower-cost emerging markets," it said.
US foreign affiliate sales in Europe are four times US exports to Europe and European affiliate sales in the United States are three times higher than European exports.
AmCham warned ripple effects from the trade conflict could damage these close ties.
The report's lead author Daniel Hamilton said intra-firm trade making up about 90% of Ireland's and 60% of Germany's trade could be hit.
There was also a risk of spillover into services trade, data flows or energy, with Europe reliant on US LNG imports.
"Ripple effects of conflict in the trade space will not be confined to trade. They ripple through all of those other channels and the interactions are quite significant," he said.
US and European companies had interlinking value chains to be globally competitive, such as for BMW cars exported from the US.
"I'm not sure you're going to have isolated investments," Hamilton said. "That's just going to make things very inefficient."