Israel is obviously the one calling the shots. They're the ones at war. It's their men and women getting killed.

Israel is a nuclear power for gods sake, and a major arms manufacturer. The US can't stop them from defeating Hamas, and Iran, if they choose to do so.

The only thing the US can do is try to influence Israel to kill fewer Gazans and Iranians in the process. That's the purpose of all these arms deliveries to Israel: all these fancy weapons make it easier for Israel to defeat Hamas in a precise way, without just killing every single Gazan in the process. If Israel's only goal was to win at any cost they could have just blockaded Gaza, preventing food and water from being donated, and simply starved everyone until they were willing to exchange hostages for food.