The agreement between world powers and Iran over its nuclear program provoked sharp reactions Tuesday across the Arab world, with some hoping the diplomatic success would reduce tensions and others fearing it would empower Iran and increase instability. The deal added a new, unpredictable factor to a region where many major players are closely allied with or supported by either Shiite Iran or Sunni Saudi Arabia , and any gain by one is often seen as a loss by the other. For decades, the United States has been closer to the Saudi camp, so the agreement – and the great effort President Obama invested in reaching it – led parties on both sides to suspect it marked a strategic realignment, with the United States moving away from its traditional Sunni allies. That feeling has caused alarm in Saudi Arabia, which has long counted on its alliance […]