Vowing to “avenge Egyptian blood,” Egypt’s military forces on Monday unleashed abrupt-yet-foreseeable airstrikes on ISIS targets in Libya. The early-morning bombing came as a rapid response to ISIS’ release of a gruesome video showing the execution of 21 Coptic Christian hostages, who had reportedly been held hostage since January. Egypt is currently not part of the U.S.-led anti-ISIS coalition striking militant targets in Iraq and Syria since August 2014, but events in Libya and a militant insurgency in the Sinai may force President Abdel Fattah al-Sisi to ramp up his plan of action. Is Egypt’s aerial campaign a quick, jabbing...