In March 2017, an engineer at G.E. Aviation in Cincinnati received a request on LinkedIn. The engineer, Hua, is in his 40s, tall and athletic, with a boyish face that makes him look a decade younger. He moved to the United States from China in 2003 for graduate studies in structural engineering. The LinkedIn request came from Chen Feng, a school official at the Nanjing University of Aeronautics and Astronautics, in eastern China. Days later, Chen sent him an email inviting him to the university to give a research presentation. Hua arranged to arrive in May, so he could attend...