Did Roth really not ask 'who gave the order'?
It was obvious enough for Roth to realize that it was Micheal along and then it was obvious enough for Micheal to know that it was Roth all along.
Roth certainly knew Michael gave the order to have Green killed, but when he says that to Mike it is really a rhetorical question.
Michael just had asked Roth who ordered Pentangeli's murder, so in effect Michael is suggesting to Roth that he is wise to Roth's deception. By making the speech about Moe Green, Roth is saying to Michael, "I may have killed Pentangeli, but you killed Moe Green. I never asked who did it, and I let it go because thats our business....now either put the money on the table or don't."
