US Comex copper futures jumped more than 12 percent to a record high after Trump announced the planned tariffs, which came earlier than the industry had expected, and the rate was steeper.

Trump told reporters at a White House cabinet meeting that he planned to make the copper tariff announcement later in the day but he did not say when the tariff would take effect.

"I believe the tariff on copper, we're going to make 50 percent," Trump said.

After Trump spoke, US Commerce Secretary Howard Lutnick said in an interview on CNBC that the copper tariffs would likely be put in place by the end of July or August 1. He said Trump would post details on his Truth Social media account sometime on Tuesday.

Trump had yet to formally announce the tariffs by Wednesday evening and several countries, mining companies and trade groups said they were awaiting firm details.

Analysts with RBC Capital Markets said they expect short-term volatility in copper prices and shares of copper companies should the tariff be implemented.

In February, the administration announced a so-called Section 232 investigation into US imports of the red metal. The deadline for the investigation to conclude was November, but Lutnick said the review was already complete.

"The idea is to bring copper home, bring copper production home, bring the ability to make copper, which is key to the industrial sector, back home to America," Lutnick said.

The National Mining Association declined to comment, saying it preferred to wait until details were released. The American Critical Minerals Association did not immediately respond to requests for comment.

Copper is used in construction, transportation, electronics and many other industries. The US imports roughly half of its copper needs each year and only has three copper smelters.

Major copper mining projects across the US have faced strong opposition in recent years due to a variety of reasons, including Rio Tinto and BHP's Resolution Copper project in Arizona and Northern Dynasty Minerals' Pebble Mine project in Alaska.

Shares of the world's largest copper producer, Phoenix-based Freeport-McMoRan, shot up more than 5 percent at one point in Tuesday trading. The company, which produced 1.26 billion pounds (571,530 metric tonnes) of copper in the US last year, did not immediately respond to a request for comment.

Freeport, which would benefit from US copper tariffs but worries that the duties would hurt the global economy, has advised Trump to focus on boosting US copper production.

Countries set to be most affected by any new US copper tariff would be Chile, Canada and Mexico, which were the top suppliers to the US of refined copper, copper alloys and copper products in 2024, according to US Census Bureau data.

Chile, Canada and Peru, three of the largest copper suppliers to the US, have told the administration that imports from their countries do not threaten US interests and should not face tariffs. All three have free trade deals with the US

Mexico's Economy Ministry and Canada's Finance Ministry did not immediately respond to requests for comment, while Chile's Foreign Ministry said it had not received any formal communication about the tariffs.

Chile's Mining Ministry declined to comment. Chairman Maximo Pacheco of Codelco, the country's top copper miner, told Reuters the company wanted to know which copper products would be included and if the tariff would hit all countries.

Pierre Gratton, president of the Mining Association of Canada, said the tariff is concerning for copper smelters such as Glencore's Horne facility in Quebec. Gratton added he was waiting for the 232 report from Trump officials.

A 50 percent tariff on copper imports would hit US companies that use the metal because the country is years away from meeting its needs, said Ole Hansen, head of commodity strategy at Saxo Bank.

"The US has imported a whole year of demand over the past six months, so the local storage levels are ample," Hansen said. "I see a correction in copper prices following the initial jump."