SHENZHEN (REUTERS) - Chinese drone giant DJI Technology built up such a successful US business over the past decade that it almost drove all competitors out of the market. Yet its North American operations have been hit by internal ructions in recent weeks and months, with a raft of staff cuts and departures, according to interviews with more than two dozen current and former employees. The loss of key managers, some of who have joined rivals, has compounded problems caused by US government restrictions on Chinese companies, and raised the once-remote prospect of DJI's dominance being eroded, said four of the people, including two senior executives who were at the company until late 2020. About a third of DJI's 200-strong team in the region was laid off or resigned last year, from offices in Palo Alto, Burbank and New York, according to three former and one current employee. In February this year, DJI's head of US R&D left and the company laid off the remaining R&D staff, numbering roughly 10 people, at its flagship US research centre in California's Palo Alto, four people said. DJI, founded and run by billionaire Frank Wang, said it made the difficult decision to reduce staffing i...