For more than half a century, conflict between Israel and the Arab nations that surround it has been a defining feature of the Middle East, producing periodic wars, lost opportunities for trade and uncountable hours of fruitless diplomacy. The rift is far from resolved. Yet there’s been a shift. Israel has made peace deals with four Arab countries late this year, underscoring that it’s now Iran — rather than Israel — that’s the common enemy uniting many Arab rulers.