Wall Street tumbles as Donald Trump escalates trade dispute with China

Jerome Powell says will 'act as appropriate' to support growth as indexes fall.

Wall Street's three main indexes lost more than 1% on Friday after President Donald Trump ordered U.S. companies "to immediately start looking for an alternative to China" in response to Beijing's threat to impose retaliatory tariffs on U.S. goods.

Trump gave no detail on how he might proceed with any such order, although he said he would be offering a response later on Friday.

Earlier in the day, China vowed to impose additional tariffs on goods worth $75 billion that include agricultural products, crude oil, small aircraft and cars. Tariffs on some products would take effect on September 1 and others on