U.S. trading partners are weighing responses after President Donald Trump’s latest action on tariffs sparked a stock market selloff Monday. The White House sent letters yesterday to about a dozen countries laying out the rates at which imports would be taxed—ranging from 25% to 40%—if no other trade agreements are reached.

Its new deal with Vietnam and its fresh tariff threats issued to many other countries seem designed to reduce China’s role in their supply chain. Countries that had hoped to stay out of the new cold war now fear they are being forced to pick a side. To appease the world’s biggest market, they must anger the world’s biggest trader.

China warned the Trump administration on Tuesday against reigniting trade tension by restoring tariffs on its goods next month, and threatened to retaliate against nations that strike deals with the United States to cut China out of supply chains.