Why did kakashi kill rin ?

[Kurama999]

This was how Kakashi was ANBU assassin.

Madara plan;
He control Mist kage to kidnap Rin and seal the 3 tails beast inside.
And before that, making sure that the Mist to take Obito body.
By seeing Kakashi killing Rin, Obito then can activate his sharingan eye.

 

[Xāvî1]

kakashi did not kill rin, rin just committed suicide.

 

[BenjerminGaye]

Kakashi read the stone tablet and wanted the mongekyou sharingan. You know the rest