President Donald Trump moved the American Embassy in Israel to Jerusalem, breaking with those who said it would ignite the Muslim world. He withdrew from the Iran nuclear deal and ordered the killing of a top Iranian general, defying those who said those moves would lead to war. He brokered treaties between Israel and two Arab states, disproving those who said such deals could only follow the creation of a Palestinian state. Again and again in the Middle East, where volatility has burnished or battered previous presidential legacies, President Trump has run roughshod over conventional thinking, advancing key policy aims or fulfilling campaign promises in ways that experts warned could set off a conflagration or blow up in his face.