U.S. protectionism is self-defeating and a "symptom of paranoid delusions" that must not distract China from its path to modernization, Chinese state media said on Friday as Beijing kept up with its war of words with Washington over trade.

U.S. President Donald Trump threatened on Monday to hit $200 billion of Chinese imports with 10 percent tariffs if China retaliates against his previous targeting of $50 billion in imports.

China's commerce ministry accused the United States on Thursday of being "capricious" over bilateral trade issues and warned that the interests of U.S. workers and farmers would ultimately be hurt by Washington's penchant for brandishing "big sticks".

The official China Daily said in an editorial the United States had failed to understand that the business it does with China supported millions of American jobs and that the U.S. approach was self-defeating.

The English-language paper cited research by the Rhodium Group saying that Chinese investment in the United States declined 92 percent to $1.8 billion in the first five months of the year, its lowest level in seven years.

"The woes the administration is inflicting on Chinese companies do not simply translate into boons for U.S. enterprises and the U.S. economy," it said in an editorial headlined "Protectionism symptom of paranoid delusions".