For more than half a century, the Japanese government has encouraged rice farmers to grow less of the crop so that prices of the national staple grain remained relatively high and steady.

Now, under an ambitious agricultural policy announced this year, Tokyo is preparing for a reversal, envisaging a future of bountiful output that would secure the country's food security without sending prices into freefall and hurting its politically influential farmers.

The new direction has taken on an unexpected urgency as Japan grapples with a shortage of the all-important staple, which has prompted a historic spike in prices, a flood of imports, and interest from U.S. President Donald Trump, who has renewed pressure on Japan to buy American rice as part of the allies' elusive trade deal.