A surge of diplomacy and an outburst of violence in the days since world powers reached a deal with Iran illustrate both the promise and the peril of what could be the start of a more peaceful era in the Middle East — or the beginning of a new round of bloodletting.

The announcement of the six-month accord on Iran's nuclear program, hailed by U.S. President Barack Obama as an opportunity to reverse decades of hostility between Washington and Tehran, has quickly been followed by indications of the deal's potential to unlock other regional conflicts.

Iranian Foreign Minister Mohammad Javad Zarif traveled this week to the Sunni Arab states of Qatar, Kuwait and Oman; his counterpart from the United Arab Emirates visited Tehran last week. The trips are the first signs of a thaw in relations between Persian Gulf Arab states and Iran's Shiite government since the ongoing revolt against Syrian President Bashar Assad polarized the region along sectarian lines.