Yunis Abbas is one of several men who has been charged in connection to the 2016 heist -- and he did an interview with Vice News ... dishing on what he says went into the planning and execution of the stick-up job where they walked away with millions in stolen jewelry.

He explains that they were tracking Kim on social media and through her show, and kept tabs on her when she came to Paris that year ... detailing her movements, much of which were being covered by the press and by social media -- her own and others.

Abbas explains they noticed Kim was showing off a lot of jewelry online and in person -- and they figured she had a lot of money ... especially from what they could see on 'KUWTK.'

It sounds like Abbas and co. were doing weeks of planning, and when the day came ... he says they hatched their plan to a T -- although he says he stayed downstairs while his associates went up and did the deed. He makes it seem like it was relatively easy to pull off.

Abbas goes on to say that he wasn't really aware of Kim at first -- more so Kanye -- and when asked if he regrets his part in the crime ... the dude says, absolutely not.

His rationale boils down to this ... he saw Kim "throwing money away," and justifies his actions by saying he was simply picking up what he thought she clearly didn't care about. So, no real remorse -- although he acknowledges she must've been traumatized from it all.

Kim herself has spoken on the aftermath at length ... saying she was scared for her life, and that she'd be harmed well beyond what actually happened. It also fundamentally changed her behavior going forward, especially when it came to security and flaunting jewelry.

It's pretty fascinating to hear the tale from one of the suspects themselves. Abbas hasn't been shy about speaking on his involvement -- he's written a tell-all book about it since then, but at the same time ... has also reportedly pled not guilty to the charges against him.