MOSCOW, July 4 -- At a Rosneft filling station in Rostov-on-Don late last month, Irina had been in line for forty minutes. The sign above the pumps capped each fill at thirty liters. Jerry cans were not permitted at all. "I'm deeply frightened by the uncertainty and the lack of understanding where the situation is heading," she said.

That anxiety, spreading from Rostov to Moscow to the Russian Far East, is what brought Kremlin officials to a solution they would have considered unthinkable three years ago. Russia, once one of the world's largest exporters of jet fuel, is now buying it from Japan.

At least 200,000 barrels of aviation fuel are set to load at the Chiba refinery southeast of Tokyo in the first half of July. The cargo will tr...