The United States Wednesday vetoed a U.N. Security Council resolution that would have called for a humanitarian pause in the fighting in Gaza as well as for Israel to rescind its order to 1.1 million Gazans to leave their homes and move to the south of their enclave.
https://www.youtube.com/watch?v
It would put Israel "on the back foot" in regards to the conflict. Israel would be tied up negotiating for hostage release which is exactly where Hamas wants them. It stops being a question of who is winning a battle and turns it into "how much is Israel willing to sacrifice".