JERUSALEM—Israeli Prime Minister Naftali Bennett on Sunday made a historic trip to the United Arab Emirates, the first visit by an Israeli premier, as part of a blitz of regional diplomacy against the backdrop of struggling nuclear talks with Iran. Israel has watched with concern as Iran has pushed a hard line against negotiators meeting in Vienna, at once demanding sanctions relief while accelerating its nuclear program. In recent weeks, Israel has dispatched its top diplomat and its defense and spy chiefs to meet allies in Europe, the United States, and the Mideast to push for a firmer approach to Iran. The Israeli outreach has been accompanied by repeated threats to take military action against Iran if diplomacy fails. Bennett’s trip to Abu Dhabi, where he will meet with Crown Prince Mohamed bin Zayed, is a milestone for both Israel and its new leader. Israel and the UAE last year …