In one case, cybersecurity expert Jareh Sebastian Dalke, 30, spent less than four weeks working at the NSA, the government’s huge and powerful signals intelligence agency, before he suddenly quit, citing family problems at the end of June.

In the few weeks he was at the NSA, he printed out top secret documents, and after leaving he offered them for sale in encrypted online communications to what he thought was an agent of a foreign government.

But he was actually dealing with an undercover FBI agent.

The foreign government was not identified by the Justice Department.