unfair treatment of the Uchiha clan in the village pushed them to the idea of a coup d'etat
Fugaku, the head of the clan and also the main organizer of the coup, encouraged Itachi's advancement in the ranks of the Anbu and wanted to use his son as a spy.
Itachi, however, understood that the coup planned by the Uchihas would lead to the intervention of other states, and, as a consequence, to a new shinobi world war, which could not cause his approval.
From this point on, Itachi's relationship with his family becomes even more strained, and his warnings to reconsider his actions fall on deaf ears.
Instead of supporting the clan, Itachi becomes a double agent and reports the clan's activities to the Third Hokage and the Konoha Council, in the hope that they will find a way to resolve the conflict peacefully
Although the Third Hokage still wanted to negotiate with the Uchiha clan, Danzo decided that there was no way out that could save the lives of the Uchihas. He explained this to Itachi and gave him a choice: to support the clan's coup, which, in his opinion,
will lead to his complete extermination of the Uchiha including Sasuke, or destroy the clan with his own hands before the coup itself begins, and get the opportunity to spare his younger brother...