In March, the U.S. Department of Homeland Security and the Federal Bureau of Investigation issued a troubling alert: Since the same month two years before, Russian state-sponsored hackers had been infiltrating the nation’s electricity grid and various infrastructure industries, including aviation, collecting information on how the networks were organized and what systems’ controls they had in place.

The fight over how far President Trump will go to protect America's steel and aluminum industries now rests largely in the hands of Commerce Department officials, who face a flood of applications from American companies seeking exemptions from Trump's newly imposed tariffs.