Two years after President Abdel Fattah el-Sisi led a military takeover promising to restore order and security in Egypt, he faces a rising jihadist insurgency that has shaken the stability of this most populous Arab state, a key ally of the United States.

Just two days after militants assassinated Egypt’s top prosecutor on a Cairo street, the military on Wednesday called in F-16 war planes and helicopters to beat back a coordinated assault in Northern Sinai by a jihadist group affiliated with the Islamic State. Egyptian soldiers were killed, police officers were trapped in their posts, ambulances were paralyzed by booby-trapped roads and residents were warned to stay indoors by jihadists roaming on motorcycles.

The scale and complexity of the attack far exceeded any of the group’s previous strikes in Sinai, raising the possibility that it has begun to coordinate more closely with the Islamic State leadership based in Syria, experts said. […]