Keep your friends close, and your enemies closer

Rating: Null/10 (6 June 2005)

I have a question for all you GF experts:(SPOILER) When Michael is talking to Frank Pantangeli at his old house, he tells Frank that his father (Don Vito) taught him to "keep your friends close, but your enemies closer". In the 40+ times I have seen this movie, I still don't understand that line at all. I know it is a Corleone family trait to make nice with a potential enemy and then kill him when he least expects it, Ir Pauly the driver and Sollozzo, but there has to be more to it than that.
Also, another line from GFII has always bothered me, when Michael is eating an orange (of course) and talking about killing Hyman Roth, he says to Rocco, "If history has taught us anything, it's that anyone can be assassinated", which in my (admittedly, mediocre) mind is nonsense. If "anyone" can be assassinated, then I think Hitler, Stalin, Mao, Khomeini, Saddam, Bin Laden, etc... easily disprove that theory. All were worthy of assassination by any definition, yet none died from outside assistance.