Possible he had a real source?

Possibly, but I can't imagine a writer taking that kind of chance at the height of the Cold War just for verisimilitude.

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lukan 6 hours ago | parent [-]

I mean, the way I imagine it is he chatted with one ore more guys and after a while he got bits here and there he was technically not supposed to have, not enough of its own, but with imagination enough to get the rough picture of how it worked and got very close. But I don't think conscious braking of classified information happened. More carelessness I guess.

	▲	bombcar 5 hours ago \| parent [-]
		That's what I've heard - intelligent research, combined with unclassified facts gleaned from conversations at coffeeshops and bars, led to a pretty accurate picture.