Insurgents carried out coordinated attacks in Egypt's volatile Sinai peninsula early Thursday that killed at least 15 soldiers and three civilians, setting off a major reprisal operation that continued throughout the day, Egyptian security officials said.
The strikes, in which the assailants were said to have employed vehicle bombs, automatic weapons and rockets, were the most serious in the northern Sinai since January, when Islamic militants staged a series of bombings against security targets in several northern towns. Those blasts left more than 40 people dead, some members of the security forces and some of them civilians.
Three months prior to that, more than 30 Egyptian troops were killed in a multipronged attack by Islamic militants, a strike to which Egypt responded by leveling large parts of the border town of Rafah to create a buffer zone between Egyptian territory and the Gaza Strip.
Hours after Thursday's attacks, attack helicopters buzzed overhead and troops flooded the area, searching for the assailants.
Egypt has been battling a reinvigorated insurgency in the rugged peninsula since the toppling of Islamic president Mohamed Morsi in July 2013. The current government of President Abdel Fattah Sisi, the former military chief who ousted Morsi, charges that Islamist groups were able to take root in Sinai during the Islamist leader's yearlong reign.
Hundreds of Egyptian soldiers and police have been killed in Sinai fighting over the last 21 months, but security forces have been unable to quell the insurgency.
There was no immediate claim of responsibility for Thursday's strikes, but because of the relatively sophisticated methods employed, suspicion fell on one of the most effective and dangerous of the Sinai militant groups, formerly known as Ansar Bayt al-Maqdis. The group has changed its name to Sinai Province and declared its loyalty to the Islamic State.