Key Takeaways Shares of steel and aluminum manufacturers jumped Monday after President Donald Trump said he planned to implement new tariffs on imports of the two metals.Trump also said he would be slapping retaliatory tariffs on countries that put tariffs on U.

The president’s plan to impose 25 percent tariffs on foreign steel and aluminum could protect U.S. suppliers, while increasing costs for others.

President Donald Trump's tariffs on steel imports this week are likely to wreak havoc on American auto manufacturing, industry leaders say.