The Trump administration says that the tariffs on metals imports are aimed at boosting domestic industries and addressing "trade imbalances."

Copper traders were caught flat-footed after refined copper was exempted from Trump's new tariffs. The exemption triggered a 20% drop in copper futures on the COMEX exchange. Traders now face excess inventory, with COMEX stockpiles at a 21-year high.

Copper traded in New York dropped about 18 per cent to $4.60 a pound in tumultuous trading after the president’s announcement. Futures had surged to a record high of nearly $6 earlier this month when Trump announced the copper tariffs, but declined to provide specific details on which products they would apply to.