The European Union is set to impose tariffs Friday on billions of dollars worth of American goods -- including jeans, bourbon and motorcycles.
The action is the latest retaliation against U.S. President Donald Trump's decision to slap import tariffs on steel and aluminum from around the globe.
The U.S. is scheduled to start taxing more than $30 billion in Chinese imports in two weeks.
China has promised an immediate retaliation, a measure that would put the world's two largest economies at odds.
John Murphy, a U.S. Chamber of Commerce senior vice president, estimates that $75 billion in U.S. products could be subjected to new foreign tariffs by the end of July.
"The U.S. is abusing the tariff methods and starting trade wars all around the world." said a spokesman for China's Commerce Ministry.
"Clarity (is) still lacking about how far things will ultimately go between (the) U.S. and China and the potential ripple effect for world trade," said financial analyst Mike van Dulken.
During his presidential campaign, Trump promised to apply tariffs because he said countries around the world had been exploiting the U.S.
The European stock market was bracing itself in the face of the new tariffs .
In early Friday trading London's FTSE 100 index of major blue-chip firms rose 0.2 percent to 7,571.78 points (compared with Thursday's closing level.)
In the eurozone, Frankfurt's DAX 30 was unchanged at 12,507.72, while the Paris CAC 40 gained almost 0.3 percent to 5,330.5 points.
But that could all change after the reality of the tariffs takes hold.
"We've never seen anything like this," at least not since the Great Depression, said Syracuse University economist Mary Lovely.
A former White House trade advisor says Trump "has been so belligerent that it becomes almost impossible for democratically elected leaders - or even a non-democratic leader like (Chinese President) Xi Jinping - to appear to kowtow and give in." Phillip Levy, a senior fellow at the Chicago Council on Global Affairs, said, "The president has made it very hard for other countries to give him what he wants."
