Does the flap of a butterfly's wings in Brazil set off a tornado in Texas? Not necessarily, but a labor dispute on the West Coast of the United States has caused 3,135 Japanese McDonald's to restrict their sales of french fries. The dispute, between 20,000 dockworkers and the shipping lines that employ them at 29 ports, has lengthened the time it takes to get the required tonnage of frozen fried potatoes to Japan from two to four weeks.

The dispute, combined with rail service delays, record levels of imports into the US, and other factors, means that McDonald's restaurants in the country will only be able to sell small portions of french fries over the busy new year period. Spokesperson Kokoro Toyama told Reuters that the situation was so dire that without the sales restriction, McDonald's Japan "would run the danger of running out of fries at some of our stores around the end of the year or beginning of the new year." The company cannot yet say when medium and large portions will be back on the menu.

Japan's 3,135 McDonald's will only serve small portions of french fries

Reuters reports that Japan imported $336 million of US-grown frozen potato products last year, making it the largest consumer in Asia. Deprived of its vital crop, McDonald's Japan has orchestrated emergency supply runs. The company has now flown in 1,000 tons of frozen fries by air, but another 1,600 tons, launched from ports on the United States' East Coast, won't arrive until January.

But there's no restriction on how many small portions you can buy

McDonald's — usually called "Makudo" in the Kansai region, or "Makku" elsewhere in Japan — has seen its image tarnished this year after a series of supply chain problems and scandals. In July, a video showed the company's chicken supplier, Shanghai Husi Food, using expired meat to make chicken McNuggets at its plant in China. Sales dropped more than 20 percent in many of the company's Japanese locations — a problem compounded when it was revealed that McDonald's was overcharging for its McNugget replacements. The Japan-only Tofu Shinjo nuggets, made of puréed fish, tofu, and vegetables, were sold for ¥150 ($1.27), rather than ¥120 ($1.02).

The fast-food enterprise has tried to win back customers with a range of limited-edition products, including a markedly unappetizing black burger, but Japanese fast food connoisseurs such as The Verge's own Sam Byford point out that rivals Burger King had the idea first. Company managers hope the new fry-denial policy will preserve potato supplies and keep customers happy, but there seems to be one problem with the scheme — there's no limit on how many small portions of french fries you can order.