Amazon.com, which is struggling to quell workplace movements from the U.S. to Europe, faces a growing union effort in Asia’s second largest economy.

A group of 15 subcontracted drivers in the city of Nagasaki is protesting the long hours and excessive number of deliveries in the absence of overtime pay. They blamed Amazon’s vaunted artificial intelligence algorithms for exacerbating their plight, by setting impossible deadlines and routes. The group formed a union this week and joined drivers in Yokosuka, Kanagawa Prefecture, who organized in June.

Amazon, which prides itself on optimizing the efficiency of its operations, has drawn criticism for how its management techniques affect warehouse workers and logistics personnel. The Seattle-based company is on the defensive as workers unionize worldwide. Amazon warehouse workers in Staten Island, New York, voted to join the company’s first U.S. union this year.