[Snapple]

The CIA stops leaks by leaking something to a government person and seeing if that leak turns up in the papers.

That's one way they stop leaks. They tell someone in the government a secret and watch if it turns up in the papers.

If they only told that one person, then he is a leaker.

So they stop leaks with leaks.

[Southack]

"The CIA stops leaks by leaking something to a government person and seeing if that leak turns up in the papers."

Yes. That sort of intelligence operation is known as a "drip."

Drips show you where your leak is located.