Reacting to a new round of Chinese tariffs imposed on U.S. goods, President Donald Trump said Friday, August 23 he "hereby ordered" U.S. companies to "start looking for an alternative to China" – and he pledged to respond formally within hours, USA Today reports.

In a series of tweets posted before he flies to France for the G-7 meeting of world leaders – where the global economy and trade issues will take center stage – Trump blasted China's latest action and vowed to announce retaliatory moves soon.

Markets plunged Friday as it became clear the trade war between Washington and Beijing was escalating. The Dow Jones Industrial Average was off by more than 500 points in midday trading, following a series of dramatic declines last week.

Trump said he would respond to the latest tariffs "this afternoon."

"Our great American companies are hereby ordered to immediately start looking for an alternative to China, including bringing our companies HOME and making your products in the USA," Trump wrote.

"We don’t need China and, frankly, would be far better off without them," he added.

White House officials did not respond to questions about what actions, specifically, Trump was referring to as pundits opined on social media that the president cannot easily order companies to pursue other markets. His posts came hours after Chinese officials announced in state media they will impose tariffs ranging from 5% to 10% on an additional $75 billion in U.S. goods, further increasing trade tensions.