WASHINGTON — The effects of President Trump’s trade war are beginning to ripple through the United States economy as steel tariffs disrupt domestic supply chains and global trading partners retaliate against a wide variety of American products, such as peanut butter, whiskey and lobster.

The cascade of tit-for-tat tariffs has spooked corporate executives, potentially slowing investment, and the Federal Reserve suggested this week that it might have to rethink its economic forecasts if the trade wars continue.

On Friday, Mr. Trump only added fuel to the fire when he threatened in a tweet to impose a 20 percent tariff on all European cars coming into the United States if the European Union did not remove its auto tariffs. “Build them here!” the president wrote.

Mr. Trump, who campaigned on a get-tough approach to trade, has said his tariffs would make trade pacts more fair and ultimately help American workers, farmers, manufacturers and other. But the situation could soon become politically perilous to Mr. Trump, whose trade policies are starting to inflict economic pain across the country, including in areas that are home to the voters who helped him win election.