Copper shipments into the United States are expected to accelerate in the coming weeks in a final scramble to get metal across the border before U.S. President Donald Trump's higher than expected 50% tariff on imported copper takes effect.

“The U.S. has been sucking in lots of copper that it didn’t really need from around the world,” Albert Mackenzie is a copper analyst at Benchmark Mineral Intelligence. President Trump had signaled that the tariffs were coming months ago, prompting many U.S. buyers to stockpile copper ahead of time.

The move injects fresh turmoil into a strained bilateral relationship as Prime Minister Mark Carney negotiates a new economic partnership with the United States.

U.S. President Donald Trump's 50% tariff on copper has placed a record premium on prices of the metal in the United States that is likely to ease over the coming months as a stockpile created by traders anticipating the levy works through the system.