Much has been written about the "danse macabre" that constituted the dialogue between Michael and Roth, and much of it centers on Michael's plan to kill him. What I am wondering is whether or not Roth ever bought Michael's claim that Frank Pentangeli tried to have him assassinated. Obviously Roth knew about Frank and his troubles with the Rosato brothers, and he backed the Rosatos probably because he thought Frankie was weal and/or he could get Michael to go along.

He also had to know that Frank had been loyal to Michael for years, and to Vito before that. Armed with all this information Roth would have also had to know that Frankie did not understand much about "big deals" and that there was no way he could engineer a complex assassination attempt at Lake Tahoe where he went to get Michael's permission to kill the Rosatos. In truth Frankie didn't know what Michael's answer would be, so he would have had to arrange the whole thing the night of the shooting.

So if Roth wasn't buying it, then each man knew before they went to Cuba that the other was going to try to whack him.