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Good morning.

Here’s what you need to know:

It’s not at all quiet on the trade front

• The U.S., already locked in a contentious dispute with China, will begin imposing steel and aluminum tariffs on Canada, the European Union and Mexico at midnight.

The measure could provoke retaliation against American businesses.

• Separately, federal regulators have proposed softening the so-called Volcker Rule, which was imposed after the global financial crisis and intended to prevent banks from making risky bets with depositors’ money. They said it was too complicated to enforce.

ABC and the “Roseanne” uproar

• In the social media age, every minute in corporate crisis management counts.

The praise the network received after swiftly axing its hit sitcom over a racist tweet could inspire other businesses facing public relations disasters. Our reporter spoke with communications experts about some of the lessons.

We also looked at the pressures facing the writers and other staff members on “Roseanne.” Although they were heartened by the show’s success, Roseanne Barr’s often divisive posts on Twitter were a growing distraction. “She would tweet stuff, then apologize and get off Twitter, and then it would get better,” an executive producer said. “And then it would blow up again.”