Big international news: Egypt has launched air strikes against ISIS.

The gruesome beheading of 21 Egyptian nationals has prompted Egypt into military action.

Egyptian jets have bombed Islamic State (IS) targets in Libya, a day after the group there released a video showing the beheading of 21 Egyptian Christians.

It was the first time Egypt announced military action against Islamist targets in its western neighbour, having previously denied it targeted militants there.

Egypt said the dawn strike hit militant camps, training sites and weapons storage areas in neighbouring Libya, where civil conflict has plunged the country into near anarchy and created havens for armed factions.

While Cairo is believed to have provided clandestine support to a Libyan general fighting a rogue government in Tripoli, the mass killings pushed president Abdel Fattah al-Sisi into open action, expanding his battle against Islamist militancy.

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“Your armed forces on Monday carried out focused air strikes in Libya against Daesh camps, places of gathering and training, and weapons depots,” the military said in a statement, using the Arabic word for IS.

Libya’s air force said it also participated in Monday’s attack.

“There are casualties among individuals, ammunition and the (Islamic State) communication centres,” Libyan air force commander Saqer al-Joroushi told Egyptian state television, adding that between 40 to 50 militants were killed.

It was not possible to confirm those numbers.

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Witnesses told news agency AFP there were at least seven air strikes in Derna in the east, a hotbed of militancy since Libyan dictator Moamar Gaddafi was overthrown in 2011. It was not immediately clear whether other areas were also hit.

State television showed footage of Egyptian fighter jets it said were taking off to conduct the strikes.

“Avenging Egyptian blood and retaliating against criminals and killers is a duty we must carry out,” the military said.

The air strikes came hours after Mr Sisi threatened a “suitable response” to the killings of the Copts, who had travelled to Libya seeking work.

Mr Sisi, a former army chief, faced a chorus of demands to retaliate after the beheadings.

This post originally appeared on the ABC and was republished here with full permission.