(AP) -- The United States hiked tariffs on Chinese imports Friday and Beijing said it immediately retaliated in a dispute between the world's two biggest economies that President Donald Trump says he is prepared to escalate.
Washington increased tariffs at 12:01 a.m. Eastern time on $34 billion worth of Chinese imports, a first step in what could become an accelerating series of tariffs.
A Chinese foreign ministry spokesman, Hu Chunhua, said retaliatory measures "took effect immediately." Hu gave no details, but Beijing earlier said it would match the U.S. action by targeting $34 billion of American goods including soybeans, pork and electric cars for higher duties.
Companies worry the spiraling dispute could chill global economic growth, but financial markets took Friday's developments in stride.
Japan's main stock market index, the Nikkei 225, gained 1.1 percent while the Shanghai Composite Index added 0.5 percent. Hong Kong's Hang Seng rose 0.8 percent. Shares also gained in early European trading.
On Thursday, Trump told reporters who flew with him to Montana for a campaign rally that higher tariffs on an additional $16 billion in Chinese goods are set to take effect in two weeks.
After that, the hostilities could intensify: Trump said the U.S. is ready to target an additional $200 billion in Chinese imports -- and then $300 billion more -- if Beijing does not yield to U.S. demands and continues to retaliate.
That would bring the total of targeted Chinese goods to potentially $550 billion -- more than the $506 billion in goods that China shipped to the United States last year.
The Trump administration contends China has deployed predatory tactics in a push to overtake U.S. technological dominance. These tactics include cyber-theft and requiring American companies to hand over technology in exchange for access to China's market.
Chinese officials reject accusations of theft and say no foreign company is obligated to share technology. But rules on auto manufacturing and other industries require companies to work through state-owned partners, which forces them to share know-how with potential competitors.
"The United States has blatantly violated WTO rules," said Hu, the foreign ministry spokesman. "Any unilateral pressure will be futile."
Washington has strained relations with potential allies in its dispute with Beijing by raising import duties on steel, aluminum and autos from Europe, Canada, Mexico and Japan.
Trump's confrontational outlook applies to other trading partners as well as China, said Tai Hui, chief strategist for JP Morgan Asset Management, in a report.
"This is a potential concern for the outlook of corporate investment and consumption around world," said Hui.
The official China Daily newspaper accused the Trump administration of "behaving like a gang of hoodlums" who would damage the global economy unless other countries stop them.
"There should be no doubting Beijing's resolve," the newspaper said.
The American Chamber of Commerce in China appealed to both sides to negotiate a settlement.
"There are no winners in a trade war," the chamber's chairman, William Zarit, said in a statement. It said American companies want fairer treatment but will be hurt by U.S.-Chinese tensions.
"We urge the two governments to come back to the negotiation table," said Zarit.
Wiseman and Superville reported from Washington. AP Writer Catherine Lucey on Air Force One contributed.
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