It's just American narcissism that makes you think that all good and bad things that happen in the world are because of the US.

Despite what Trump might've convinced you of, US Presidents can't just end wars by making statements. Ukraine didn't surrender because Trump stopped support of Ukraine. Israel wouldn't have either. Hamas massacred villages and took a lot of people hostage. There was nothing anyone could do to stop a war from happening. If Israel didn't have precision guided munitions they would've used big dumb bombs instead which would've meant even more casualties.

Best anyone can do is to try to reduce casualties and try to influence countries towards negotiations to end the war. Sorry to break this to you but US Presidents can't just snap their fingers and end all wars. Trump lied to you.