When there is two parties, must be belligerent, one party. So decision is that "Either you kill me or I kill you." Not that without killing... "Without being killed one of us, the fighting cannot be stopped."
Just like Jarāsandha was fighting with Bhīma. During daytime the fighting was going on, and at night Bhīma was a guest of Jarāsandha. As guest is honored, respected, all the parties... But during daytime the fighting was going on. And this fighting went on for twenty-eight days. Still, there was no decision. Then Kṛṣṇa gave hint, Bhīmasena, that "Jarāsandha has got a defect. He is joined, two bodies joined. So if you bifurcate him, then he will be killed." So later on Bhīmasena took that policy, and Jarāsandha was killed.