(Bloomberg) -- A 10% tariff on all US imports, as proposed by former President Donald Trump, would throttle a key part of the economy reliant upon trade, the chief of the nation’s largest port said.

“That would be devastating to a port like Los Angeles, and combined with our neighbor and friends in Long Beach, we account for nearly 40% of the nation’s imports,” Port of Los Angeles Executive Director Gene Seroka said in an interview Thursday on Bloomberg TV.

In August, Trump floated a 10% tax on goods imported into the US from all countries, calling it “a ring around the collar” of the economy.

The White House called the idea a “sweeping” tax on the middle class. Critics like Nobel Prize-winning economist Paul Krugman have said, although the actual hit to gross domestic product wouldn’t be huge, the move would effectively mark the end of the rules-based global trading system and invite retaliation by America’s trading partners.

Trump’s tariff plan could also put upward pressure on consumer prices at a time when inflation is tapering off and Federal Reserve officials increasingly look finished hiking interest rates.

Seroka sounded cautiously optimistic about the economy and trade heading into 2024. LA’s port posted a 19% year-on-year increase in container imports and exports last month. Through the first 11 months of the year, though, total volume is down about 14% from last year.

Business at the port of LA is expected to continue improving, he said, with a “normal cadence” of cargo flowing as companies replenish inventories. He said exports through Los Angeles have risen for several months, boosted by agricultural products and finished manufactured goods to Asia and elsewhere.

US trade with China has declined — but not plunged, he said. Last year, 57% of the goods moving through the Los Angeles port either came from or were headed to China. This year that figure is about 53%.

“It’s not fallen off the cliff like some people have estimated,” Seroka said. “We are seeing growth in Southeast Asia but not in leaps and bounds like there was speculation on earlier this year.”

--With assistance from Alix Steel and Guy Johnson.

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