In this May 9, 2019, photo, steel rods produced at the Gerdau Ameristeel mill in St. Paul, Minn. await shipment. Last week’s flareup over the Mexico tariffs may prove to be a pivotal juncture. The spat was especially alarming to businesses because it came seemingly out of nowhere. Less than two weeks earlier, President Donald Trump had lifted tariffs on Mexican and Canadian steel and aluminum, action that seemed to signal warmer commercial ties between the United States and its neighbors. (AP Photo/Jim Mone, File)