TOKYO - Japanese aluminium buyers agreed to pay premiums of $395 a ton for shipments between July and September, the highest since 2015, as the US-Israeli war on Iran squeezed supply, five sources involved in the pricing talks said.

Japan is a major Asian importer of the light metal and the premiums for primary metal shipments it agrees to pay each quarter over the London Metal Exchange (LME) cash price serve as the regional benchmark.

The agreed premiums are up from the $350 to $353 a ton paid in April to June, marking the third consecutive quarterly increase and the highest since $425 in January to March 2015.

Global producers initially sought $460 to $480 per ton for July to September shipments in late May, up 30% to 37% from the previous quarter, but gradually lowered their offers before settling at $395, the sources said.

"The deals were reached after producers reduced offers as Middle East tensions eased and European premiums softened," said a source at a Japanese rolling mill. "Buyers accepted the terms once offers fell below the psychologically important $400 mark."

A source at a Japanese trading house said the agreements were struck this week after producers made significant concessions to bring offers below $400.

The sources declined to be identified because the talks were private.

The closure of the Strait of Hormuz because of the war has disrupted supplies from the Middle East, which accounts for 9% of global aluminium smelting capacity, and curbed shipments of raw materials needed to produce the metal. Japan sourced nearly 30% of its aluminium ingot imports, including primary and alloy metal, from the region in 2025.

The conflict also directly affected output, with missile strikes hitting two Gulf smelters.

But a string of announcements last week about supply restarts has weighed on the metal prices. The war-related risk premium has largely evaporated amid a more durable ceasefire and the resumption of shipping through the Strait.

Still, concerns over the fragility of the truce remain after fresh US strikes on Iran on Tuesday highlighted the risk of renewed supply disruptions.

Aluminium stocks at Japan's three major ports fell 4.2% from a month earlier to 238 900 tons at the end of May, the lowest in nearly a decade, according to data released by Marubeni in June.