In 1991, American officials flew to Israel to keep the country from retaliating against Scud missile attacks and joining the Gulf War. In 2002, Defense Secretary Donald Rumsfeld warned it would be “in Israel’s overwhelming best interests not to get involved” in the looming invasion of Iraq. In 2026, the United States went to war alongside Israel. “It’s the first time,” said Amos Yadlin, a former head of Israeli military intelligence, “that Israel is going to war together with a superpower.” The United States has been the Jewish state’s most important backer for decades, providing it with weaponry and working...