yes sasuke was never an ally of obito but Thats the reason why Obito kept itachi alive. Obito knew about itachi and his plan with sasuke so he let itachi carry it out so obito can tell sasuke the truth later on and have him as an ally. Sasuke would have the EMS and then later on awaken the rinnegan, Thats more than obito would ask for.
If obito wanted itachi dead, he would of
-killed him himself. Obito didn't even fear Minato at the age of 14. why would he fear itachi.
-He could have the akatsuki kill him with ease.
But why didn't he? Well Plot for sure since itachi needed to fight sasuke and the fact that Obito wanted sasuke on his side.
Kyuubi needed to be hunted last so there was no reason to attack the village and making a deal with itachi would be good for obito since he could use itachi further doing other jobs for him.
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