Top copper suppliers say exports are not threatening US national security as the Trump administration considers tariffs.
Seven US trading partners formally opposed a federal investigation examining whether copper imports pose a threat to national security.
Governments argued in a public letter that now exports strengthen the US supply chain and do not hinder defense, energy or infrastructure preparation.
The investigation began on March 10th under section 232 of the Trade Expansion Act of 1962.
“Copper is an important material for the US national security, economic strength and industrial resilience,” the executive order said. “Copper, scrap copper and copper derivatives play a key role in defense applications, infrastructure and emerging technologies, including clean energy, electric vehicles, and advanced electronics. The United States faces significant vulnerability in the copper supply chain, increasingly relying on foreign sources of mining, covered copper and refined copper.”
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Chile, the largest supplier of sophisticated copper in the United States, said in a letter that its exports are essential to the American industry.
“The import of copper from Chile contributes to the security of the US supply chain and does not represent a risk to national security interests,” wrote Chilean Ambassador Juan Gabriel Valdes in a letter.
Emphasizing its role as a close ally and top destination for US copper exports, Canada noted that bilateral copper trade benefits both the economy and supports defence-related manufacturing.
The Canadian government said in its letter that “Canadian copper imports do not threaten to undermine US national security.”
“The opposite is true, in fact. Canada’s copper imports support the national security of the United States and strengthen the supply chain with complementary efforts from the domestic US industry,” they write. “Both Canadian and US copper producers are vulnerable to market manipulation by non-aligned producers across the supply chain, particularly in the copper refining segment. Canada therefore shares the US interest in reducing its reliance on imports from non-market-based producers in the non-company country.”
Peru said its exports will help meet the demand for copper used in clean energy, transportation and electronics, citing a 2024 memorandum of understanding with the US on critical mineral cooperation.
“Firstly, the Peruvian government can confidently assert that Peru’s copper exports do not pose a threat to the national security of the United States,” the country’s Ministry of Foreign Trade said. “Peru is a reliable trading partner that contributes to the security of the US copper supply chain and strengthens the competitiveness of various strategic industries such as electronics, renewable energy, automobiles and more by supplying products such as copper cathodes, copper bars, profiles, copper wires, copper plates, copper plates, strips and more.
Indonesia warned that new measures could raise costs for US manufacturers and reduce US copper exports to Indonesian buyers. The government said US companies have invested heavily in Indonesia’s mineral sector and will face uncertainty under new trade restrictions.
South Korea pointed to investment in the production of US-based batteries and electronics. South Korean officials said South Korea’s copper is primarily used in construction and private infrastructure and warned that new tariffs, not defense, could undermine industry growth.
China called the investigation unnecessary, saying that copper exports to the US are minimal. He said calling national security into trade disputes risks eroding the stability of the global supply chain.
Meanwhile, the European Union reflected these concerns, saying its exports are important to the US energy and manufacturing sector and should not be targeted.
According to Trump’s executive order, the Section 232 investigation must be completed within 270 days. This concludes the current review in November.
The agency did not release any preliminary findings and did not respond to requests for comments on the letter or updates on the status of the investigation prior to publication.
