The U.S. plans to swiftly impose tariffs on $7.5 billion in aircraft, food products and other goods from the European Union after the World Trade Organization authorized the levies Wednesday, citing the EU’s subsidies to Airbus SE.

The new duties represent the most significant trade action against the EU since the Trump administration hit the bloc with steel and aluminum duties last year, and could further sour relations between allies that have long sought to resolve trade disputes without resorting to tariffs.

“I’m...