Kautilya's Arthashastra 7.13.40

7.13.40

arimitreṇa mitraṃ ca purastād avaghaṭṭayet /
mitramitram areś cāpi mitramitreṇa vārayet //

he should also keep his frontal enemy's friend engaged in war with his own friend; and with the help of his friend's friend, he should avert the attack, threatened by the friend of his enemy's friend;