Biden’s chief diplomat, Antony Blinken, has spoken clearly, in public, about the way the US wants Israel to fight Hamas. If Israel kills anything like as many Palestinian civilians as it did in the north, in defiance of the stated will of Joe Biden, the US president will have to decide whether he can continue to give Israel so much support, not just on the battlefield but also in the United Nations Security Council, where the US has used its veto many times to protect Israel.