President Trump is forging ahead with his aggressive tariff campaign, moving on from “reciprocal” tariffs to the sector-specific tariffs he promised. To do so will involve Trump’s continued application of Section 232 of the Trade Expansion Act of 1962, which allows a president to impose tariffs to protect or bolster domestic industries if there are deemed potential national security threats. What used to be a rarely employed trade provision has been a favorite instrument. The Commerce Department previously launched Section 232 probes into copper and lumber. And earlier this month, the administration started investigating pharmaceuticals and semiconductors.  …Softwood lumber is a critical and preferred ingredient for homebuilding, and 30% of it is imported by the US. Homebuilders warn that tariffs on softwood lumber and other materials could further exacerbate the housing affordability crisis. Higher costs of lumber imports could also affect other products, such as furniture and even toilet paper.