The Trump administration has significantly widened the scope of its 50% tariffs on steel and aluminum, discreetly adding more than 400 new product categories to the list. The expanded duties, which took effect Monday, mark a major escalation in the administration’s trade policy.

The tariffs, originally aimed at core steel and aluminum imports, now apply to a broad range of goods that either contain those metals or are made from them. Newly affected items include machinery, building materials, specialty chemicals, and even fire extinguishers.

Brian Baldwin, vice president of customs at Kuehne + Nagel International AG, wrote in a LinkedIn post: “Auto parts, chemicals, plastics, furniture components—essentially anything with a metallic element or connection to aluminum and steel is likely included. This isn’t just a tariff adjustment—it represents a fundamental change in how steel and aluminum-based products are regulated.”

According to the Commerce Department, the expansion covers 407 new product groups. In a statement, Jeffrey Kessler, Under Secretary of Commerce for Industry and Security, said the move was designed to close loopholes that allowed companies to sidestep earlier tariffs. “Today’s action broadens the scope of the steel and aluminum duties and prevents circumvention—further supporting the recovery of the U.S. metals industry,” Kessler said.

The official tariff list is presented using only the detailed customs codes that classify imported goods. For instance, fire extinguishers are identified simply as “8424.10.0000,” making it difficult for the public to clearly identify the full range of products now subject to the higher duties.

Trade experts say the expansion represents a substantial increase in the economic impact of the tariffs. Jason Miller, a supply chain management professor at Michigan State University, estimated the duties now cover at least $320 billion worth of imports, based on 2024 customs data. “This is going to intensify inflationary pressures by driving up costs on top of the already rising prices domestic producers are charging, as shown in July’s Producer Price Index,” Miller noted on LinkedIn.

President Trump has leaned heavily on targeted tariffs to advance his broader trade agenda. In June, he announced that steel and aluminum tariffs would double to 50% for most foreign suppliers, a move that rattled U.S. businesses and trading partners alike. The latest expansion underscores the administration’s intent to keep tightening restrictions on products tied to the steel and aluminum industries.

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