Shares of steel and aluminum companies like Cleveland-Cliffs Inc. (CLF), Steel Dynamics Inc. (STLD), United States Steel Corp. (X), and others surged on Wednesday as U.S. President Donald Trump’s proposed tariffs took effect.

The CEOs, which include Cleveland-Cliffs Inc.’s Lourenco Goncalves, Nucor Corp.’s Leon Topalian, and United States Steel Corp.’s David Burritt, argued that avoiding exemptions was a matter of national security.

Trump's action to bulk up protections for American steel and aluminum producers restores effective global tariffs of 25% on all imports of the metals.

Global markets have been gripped by a sense of risk aversion ever since U.S. President Donald Trump triggered a tit-for-tat tariff war between the U.S. and its trade partners, which analysts have said could stoke inflationary pressures and trigger an economic slowdown.