Heavily armed militants claiming allegiance to Islamic State carried out a broad assault on Egyptian security forces in the Sinai Peninsula on Wednesday, a daylong battle that left scores of troops, civilians and extremists dead and raised the specter of full-blown warfare in the rugged enclave.
Egypt scrambled F-16 fighter jets and Apache helicopters to beat back the assault, with the fighting appearing to taper off in the evening, nearly 12 hours after it began. In a statement, the armed forces claimed to have killed 100 insurgents and acknowledged the deaths of 17 troops, although several Egyptian news reports, citing security sources, put the military death toll at more than 60.
"We are fighting a vicious war and we have the will and persistence to uproot this dark terrorism," said the military statement, which followed a meeting of top army chiefs. "We won't stop until we purify the Sinai."
The day's events marked the most serious outbreak of fighting in an Islamic insurgency that had simmered for years in the peninsula but flared after the toppling two years ago of President Mohamed Morsi, an Islamist. Sinai has not seen such heavy combat since the 1973 Arab-Israeli war.
The complexity and evident degree of advance planning of the offensive made clear that the militants pose a potent threat despite the military's efforts to contain the insurgency. Egypt has taken security measures including the carving out of a half-mile-wide buffer zone along the frontier with the Gaza Strip, which involved the demolition of hundreds of homes in the border town of Rafah.
Fighting centered in and near the northern Sinai town of Sheik Zuwaid, where militants armed with antiaircraft guns mounted on pickup trucks hit a number of checkpoints and other security targets shortly before 7 a.m., killing and wounding dozens of soldiers and police officers. The sophisticated, multipronged attack also employed car bombs and snipers on rooftops, witnesses said.
The Islamic State-linked group, which calls itself Sinai Province, boasted in a statement that it had attacked more than 15 targets including army checkpoints and police posts, and said its fighters were equipped with battlefield weapons including rocket-propelled grenades and mortars. The online statement could not be authenticated, but much of it appeared to track with events on the ground.
The offensive came a day after President Abdel Fattah Sisi vowed to take harsh new steps against "enemies" attacking the state. His angry remarks came at the funeral for the nation's prosecutor general, Hisham Barakat, who was killed Monday by a powerful bomb in Cairo. Barakat was the most senior civilian official to die at the hands of presumed Islamic militants; no known group has claimed responsibility for the attack.
The militants of Islamic State had vowed to carry out a sweeping offensive during the holy month of Ramadan, which began June 18. Groups linked to Islamic State claimed responsibility for attacks last week at a Tunisian beach resort and a Shiite Muslim mosque in Kuwait, which killed more than 60 people between them
Special correspondent Amro Hassan contributed to this report.