Who is blowing up ships in the Gulf?

SHINZO ABE hoped this was a moment for diplomacy. His visit to Tehran this week, the first by a Japanese prime minister since the Islamic revolution in 1979, was meant to reduce tensions between America and Iran. After a meeting with Iran’s president, Hassan Rouhani, Mr Abe warned that the region could “accidentally” slip into conflict. And then, a few miles off Iran’s southern coast, came an illustration of how that might happen.

On June 13th two tankers in the Gulf of Oman sent distress calls after they had been damaged by large explosions. The Front Altair, flagged in the Marshall Islands and owned by Frontline, a Norwegian shipping company, was hauling a cargo of naphtha, an oil derivative, from Abu Dhabi; the Kokuka Courageous, registered in Panama and operated by the Japanese company Kokuka Sangyo, was laden with methanol. Both were bound for Asian ports. Photos from Iranian news agencies showed a fire burning on the starboard side of the Front Altair. The plume of black smoke overhead was thick enough to appear in satellite images. One-fifth of the world’s supply travels through the Strait of Hormuz, an important chokepoint for international shipping.