(Reuters) – Egyptian jets bombed Islamic State targets in Libya on Monday, a day after the group there released a video showing the beheading of 21 Egyptian Christians, drawing Cairo directly into the conflict across its border.

Egypt said the pre-dawn strike hit militant camps, training sites and weapons storage areas in the neighbouring oil-producing country, where factional fighting has unleashed virtual anarchy and created havens for jihadi Islamists.

While Cairo is believed to have provided clandestine support to a Libyan general fighting a rogue government in Tripoli, the 21 decapitations pushed President Abdel Fattah al-Sisi into open action, expanding his battle against Islamist militancy.

“And let those near and far know that the Egyptians have a shield that protects and preserves the security of the country, and a sword that eradicates terrorism,” the Egyptian military said in a statement.

Egyptian state television aired footage of fighter planes leaving a hangar with “Long live Egypt” emblazoned on their tails, followed by night-vision aerial footage showing bomb explosions and the aircraft returning in early daylight.

Libya’s air force also participated in Monday’s attack, which targeted Derna, an eastern coastal city regarded as a base for fighters of the ultra-radical Islamic State.

“There are losses among individuals, ammunition and the (Islamic State) communication centres,” Libyan air force commander Saqer al-Joroushi told Egyptian state television, adding that dozens had been killed.

Joroushi, who is loyal to Libya’s internationally recognised government, which set up camp in the city of Tobruk after losing control of the capital Tripoli, said there would be more strikes on Tuesday.