I've been following your responses in this thread. I do agree with you but you make it seem that it's almost impossible to blend in now. Based on this, wouldn't it be almost impossible for intelligence agencies to develop human sources in modern countries? They could just trace the case officer back to their home base or just classify them as a spy based on other patterns? Doesn't this mean that human intelligence is practically dead in 1st world countries?

No not at all, it is done completely differently though.

Before when I was talking about the needle in a haystack problem which is the biggest weakness of the modern big data era.

So to give a really concrete example imagine you need to meet a source clandestinely in the past it’s lots of sneaking around doing surveillance detection routes and meeting in hotel rooms and things like that. Those days are completely dead. You stand out immediately.

Instead you’re looking to have very normal and plausible reasons to be in the same space together while remaining in a large crowd and not having contact usually outside of that.

So imagine you and I both get season tickets to the local sports team and we go there to watch a game just as regular fans and we find a way to communicate in that crowd.

Even the best data analysis / ML algorithms are only ever going to see two people going to a sports match every few weeks. There’s nothing interesting about either one of them that stands out.

It’s just a very different way of doing business basically but hopefully that’s an illustrative example to show you what I mean.