On the London Metal Exchange (LME), a tonne of copper for three-month delivery rose yesterday by 0.5% to $10,010, after gaining 1% the previous day. The symbolic 10,000-dollar threshold has been crossed once again, although the price is still slightly below last week's peak of $10,046.50.

All hell has broken loose since Donald Trump ordered the Commerce Department to investigate the possibility of tariffs on copper imports on national security grounds. Officially, this aims to boost domestic production. Unofficially, it's a rather muscular way of redefining the lines of the global supply chain.

Relocation of copper stocks in the USA

Traders did not wait for the conclusions of this investigation. On the New York Comex, the copper contract for May delivery jumped 1.6% to $5.18/lb. Arbitrage between the Comex and the LME reached an all-time high of over $1,400 per tonne. "This situation creates a powerful incentive to move metal to the US to get ahead of any taxes," explains Warren Patterson, head of commodities strategy at ING.

And the snowball effect could well grow. The US investigation covers a wide range of products: blister copper, concentrates, alloys, scrap and by-products. If tariffs are indeed introduced, prices in New York could soar even higher. Some sources even point to a possible implementation within just a few weeks - a much tighter timetable than initially envisaged.

"It's not industrial demand that's exploding, but a tactical operation to relocate stocks", says Ole Hansen, strategist at Saxo Bank. A game of anticipation rather than a real signal of structural recovery.

At the same time, global production is showing signs of vulnerability. Glencore has temporarily suspended shipments from its Altonorte smelter in Chile, due to a technical incident. The plant, capable of producing up to 349,000 tonnes of copper a year, is adding a further bullish factor to an already feverish market.

On the Chinese market, copper prices on the Shanghai Futures Exchange climbed 1.2%, briefly tipping over into backwardation - a sign that operators are anticipating short-term supply tensions. This dynamic contrasts with that of the LME, where the contango persists, with a discount of $27 per tonne, reflecting a relative easing in inventories.

However, all this is taking place in an unfavorable monetary context. The strengthening dollar, supported by solid US economic indicators, is weighing on all commodities denominated in greenbacks. A strong dollar makes copper more expensive for buyers operating in other currencies.

Movements in other industrial metals were more muted: aluminum edged back 0.1% to $2,614 per tonne, while nickel advanced 0.2% to $16,040. Zinc gained 0.6% to $2,963.50, lead 1% to $2,056, and tin 0.9% to $34,650.

Antofagasta, Freeport-McMoran, Anglo American, Glencore, Hindalco, BHP, First Quantum and Southern Copper are among the leading listed copper producers.