Butter knives, baby strollers, spray deodorants and fire extinguishers, considered “derivative” steel and aluminium products, were previously excluded from the 50 per cent tariff, though they were still subject to the higher country-specific tariffs Trump enacted over the last several months.

However, on Friday, US Customs and Border Protection and a division of the US Commerce Department published notices informing US importers that 407 categories of goods containing steel and aluminium would immediately be subject to the 50 per cent tariffs at 12.01am ET on Monday (2.01pm Tuesday AEST).

The non-steel and non-aluminium components of the products face other applicable levies.

The abrupt move leaves many US-based importers between a rock and a hard place, with goods they already paid for currently in transit.

If they decide to accept the goods, the importers will have to pay considerably higher tariffs. But if they, for instance, tell cargo operators not to unload their orders at US ports to avoid paying tariffs, they’ll likely lose money.

“Today’s action expands the reach of the steel and aluminium tariffs and shuts down avenues for circumvention – supporting the continued revitalisation of the American steel and aluminum industries,” Under Secretary of Commerce for Industry and Security Jeffrey Kessler said in a statement.

As is the case with any tariff in place, businesses may not pass on the entire tariff expense they’ve paid to consumers by raising prices.

But the chances of businesses absorbing a tariff as high as 50 per cent will likely be slimmer compared to goods tariffed at lower rates.

In addition to the 50 per cent tariff on copper-based goods that recently took effect, the levies “will likely ripple through the manufacturing supply chain, raising production costs across construction, automotive, and electronics sectors,” analysts at the Telsey Group said in a note on Tuesday.