US President Donald Trump on Friday lashed back at a new round of Chinese tariffs by heaping an additional 5% duty on some $550 billion in targeted Chinese goods in the latest tit-for-tat trade war escalation by the world's two largest economies. 

Trump's move, announced on Twitter, came hours after China unveiled retaliatory tariffs on $75 billion worth of U.S. goods, prompting the president earlier in the day to demand U.S. companies move their operations out of China. 

intensifying U.S.-China trade war stoked market fears that the global economy will tip into recession, sending U.S. stocks into a tailspin, with the Nasdaq Composite down 3%, and the S&P 500 down 2.6%. 

U.S. Treasury yields also declined as investors sought safe-haven assets, and crude oil, targeted for the first time by Chinese tariffs, fell sharply. 

Trump's tariff response was announced after markets closed on Friday, leaving potentially more damage for next week. 

 "Sadly, past Administrations have allowed China to get so far ahead of Fair and Balanced Trade that it has become a great burden to the American Taxpayer," Trump said on Twitter. "As President, I can no longer allow this to happen!" 

He said the United States would raise its existing tariffs on  $250 billion worth of Chinese imports to 30% from the current 25% beginning on Oct. 1, the 70th anniversary of the founding of the communist People's Republic of China. 

At the same time, Trump announced an increase in planned tariffs on the remaining $300 billion worth of Chinese goods to 15% from 10%. The United States will begin imposing those tariffs on some products starting Sept. 1, but tariffs on about half of those goods have been delayed until Dec. 15.