Copper and silver futures in New York surged above international benchmarks as traders ramped up bets that Trump would impose steep import tariffs on the two metals. COMEX front-month silver futures on the New York Mercantile Exchange traded at a premium of more than $0.80 an ounce to spot silver prices in London on Thursday, near their December peak. COMEX front-month copper also traded at a premium of $623 a tonne to LME copper for the same period, close to the record during the historic short...