Stocks tumbled Friday toward their worst week of 2019, as investors fretted over an escalating trade war with China.

The Dow Jones industrial average slid 334.18 points to 26,249.22 at its lowest point Friday after China vowed to retaliate over threatened US tariffs on another $300 billion worth of Chinese goods.

“We don’t want to fight, but we aren’t afraid to,” a spokeswoman for China’s foreign minister said. “If America does pass these tariffs then China will have to take the necessary countermeasures to protect the country’s core and fundamental interests.”

The S&P closed down 0.7%, marking its worst week this year. The Dow Jones industrial average capped off its second worst week of 2019 after recovering somewhat to close down 98.41 points, or 0.4%,

China’s backlash follows several weeks of trade talks between the two countries that resulted in little breakthrough. The truce was broken Thursday when President Trump, who has been concerned about China stealing US technology, tweeted that he plans to impose a 10% tax on another $300 billion worth of Chinese goods.

Analysts say the threatened round of tariffs would hit US consumers hard because it would tax the remaining $300 billion in Chinese imports that are currently tariff free.

“Total tariffs on Chinese imports could cost the average family about $1,500 per year — effectively a tax on consumers that will slow the economy,” said Dan North, chief economist at Euler Hermes North America.

Shares of iPhone maker Apple fell 2.2% to $203.90 as analysts warned that the tech giant, which assembles its iPhones in China, would be vulnerable to a price increase.

Apple could see iPhone profits take a $0.30 to $0.50 per share hit if the tariffs are enacted, according to rough estimates by Bank of America Merrill Lynch analysts,

Shares of jeans maker Levi Strauss, by contrast, jumped 3.1% to $18.88 after Reuters reported that the company has been moving production out of China due to the growing uncertainty hanging over goods imported from that country.

Levi’s Chief Executive Officer Chip Bergh told Reuters that just 1% to 2% of the company’s products sold in the US are manufactured in China — compared to 16% two years ago.

The tariff war of words had investors so rattled Friday that they ignored an otherwise positive jobs report.

“Today’s market action illustrates that the jobs report has been rendered virtually meaningless in the face of a worsening tariff situation,” said Kristina Hooper, Chief Global Market Strategist at Invesco. “And the stock market sell-off is actually less worrisome than what is happening in the Treasury market.”

The 10-year Treasury note yield fell to $1.8550 Friday. Yields move in the opposite direction to price.