I agree! with Vito that it was – Barzini all along....and Michael that it was Hyman Roth that tried to have Michael killed

Michael's greed, nearly undone himself with Roth, Michael believing Roth [and the other partners] will go along with Michael moving Klingman out – gifting Michael their hotel
and perhaps if not for the Tahoe shooting - Roth's role - Kay may have continued living the life she had chosen

Why the Tahoe assassins?
Originally Posted by Lana
Extracts:
Roth had indeed "overthought" the [Tahoe shooting] plan being fixated, in framing Pentangeli and ended up in a tangled web

In fairness to Michael, Roth was stringing Michael along among others “gifting” their Hotel and pretending “to go along” instead if Roth had been honest perhaps Michael and Roth could have worked out some mutually beneficial arrangement not dissimilar to Roth's Havana business Then both Michael and Roth could live happily for a hundred years!

How'd Michael know it was Roth?
Originally Posted by Lana
I also believe Michael understood that whilst Michael was Roth's successor, the heir apparent, Roth was always going “to hold onto his Havana empire” until Roth's retirement or death and at the time, Michael would inherit Roth's interests in the Havana operation

Anybody kinda rooting for Roth to beat Mike?
Originally Posted by Turnbull
On the other hand, Michael, who could have used violence or murder against Roth, didn't--he was negotiating for the Havana properties. Roth, on the other hand, set up the machine gun attack at Tahoe, and didn't care if Kay was killed in the attack. Moral of story: No honor among thieves