Amazon Web Services said it is closing its artificial-intelligence research lab in Shanghai, ending a seven-year effort to conduct advanced machine-learning work on the mainland. A company spokesperson described the decision as “difficult” and said AWS will offer full support to affected employees during the transition. Opened in 2018, the lab produced more than 100 academic papers and developed the open-source Deep Graph Library, which industry analysts estimate has generated roughly $1 billion in downstream revenue. The facility once employed more than 1,000 people, according to a staff scientist who said the unit is being dissolved because of “strategic adjustments amid U.S.–China tensions.” AWS’s retreat follows similar moves by IBM, which has shuttered its China research sites, and Microsoft, which is relocating parts of its local AI team. The pullback highlights the growing difficulty for U.S. technology companies to maintain large R&D footprints in China as trade frictions and regulatory scrutiny intensify.