WASHINGTON - The US Commerce Department said Tuesday that 50 percent tariffs have taken effect on 407 additional product categories containing aluminum or steel.

The new tariffs expanded the list of goods subject to Section 232 tariffs on steel and aluminum imports, covering wind turbines and their parts, mobile cranes, bulldozers, railcars, furniture, compressors, pumps, and hundreds of other products.

Customs brokers and importers in the United States (US) had little time to prepare for the abrupt move, which quietly took effect Monday, applying even to goods already in transit. It's unclear whether the metals levies stack on top of country-specific tariffs.

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"Today's action expands the reach of the steel and aluminum tariffs and shuts down avenues for circumvention -- supporting the continued revitalization of the American steel and aluminum industries," said Jeffrey Kessler, under secretary for industry and security of the US Commerce Department.

The agency identified newly targeted goods only by customs codes, such as "8424.10.0000" for fire extinguishers, making it hard for the public to determine which products are affected.

In early June, US President Donald Trump raised the tariff on steel and aluminum imports from 25 percent to 50 percent. He invoked Section 232 of the Trade Expansion Act of 1962, the International Emergency Economic Powers Act, Section 301 of title 3 of the United States Code, as well as Section 604 of the Trade Act of 1974 in the order.

READ MORE: Trump says he plans to double steel, aluminum tariffs to 50%

In late July, Trump announced a 50 percent levy on copper-based products, effective Aug 1.

Experts warned that the sector-specific tariffs would have a vast impact.

The levies "will likely ripple through the manufacturing supply chain, raising production costs across construction, automotive, and electronics sectors," CNN reported, citing an analysis.