The Justice Department announced Thursday multiple arrests in a series of complex stolen identity theft cases that officials say are part of a wide-ranging scheme that generates enormous proceeds for the North Korean government, including for its weapons program.

The conspiracy involves thousands of North Korean information technology workers who prosecutors say are dispatched by the government to live abroad and who rely on the stolen identities of Americas to obtain remote employment at U.S.-based Fortune 500 companies, jobs that give them access to sensitive corporate data and lucrative paychecks. The companies did not realize the workers were overseas.

The fraud scheme is a way for heavily sanctioned North Korea, which is cut off from the U.S. financial system, to take advantage of a “toxic brew” of converging factors, including a high-tech labor shortage in the U.S. and the proliferation of remote telework, Marshall Miller, the Justice Department’s principal associate deputy attorney general, said in an interview.