Prices rose as much as 1% to $12,044 a ton on the London Metal Exchange, extending a rally that has lifted prices by more than a third this year. The possibility that Trump will place tariffs on the metal has been a central factor driving prices higher, with a surge in US imports through the year thrusting manufacturers elsewhere into a bidding war to keep hold of supplies. The impact on global trade flows has been so extreme that prices have rallied even though underlying usage has deteriorated rapidly in China, which consumes about half the world’s copper.