The July terrorist attack in Oman is unlikely to generate domestic political backlash or economic harm, and it is unlikely to indicate a greater threat of terrorist attacks in Gulf Cooperation Council, or GCC, countries. However, the attack will likely lead to a regional security crackdown against suspected terrorists and government critics. Nearly a month has passed since Oman suffered its first terrorist attack claimed by the Islamic State. On July 15, three Omani brothers killed six individuals -- an Omani police officer, four Pakistanis and one Indian -- and injured at least an additional 28 others at the Ali bin Abi Talib Shiite mosque in Muscat on the eve of the Shiite holiday Ashura. The three militants initially opened fire from the building adjacent to the mosque and then proceeded to hold some worshippers hostage before Omani security forces released the hostages and eventually killed the three militants. The...