Today, this is known as "national security," and it's a term used to justify unethical and enormous amounts of secrecy that do not protect the public, but protect those in power and their corporate, financial and political interests."
This is exactly what Julian Assange did, and many others have and are doing, like independent alternative media outlets.
Transparency is what Julian Assange was all about, and the American empire, or more so the global empire, has been desperate to keep its secrets and prosecute anyone or anything that threatens their secrecy. That's what this is all about. And they proved that with Chelsea Manning.