Western leaders called for urgent action to defeat the "monstrosity" of Isil in Libya yesterday, as Egypt launched air strikes in retribution for the group's mass beheading of 21 Christian migrant workers.
The murder of kidnapped Egyptian Christians by Islamic State jihadists in Libya prompted Egypt's first official foreign military operation for decades, as the country's air force bombed targets linked to the militants' Libyan branch at dawn.
The simultaneous beheadings of the Christian migrant workers on the shores of Libya's Mediterranean coast had been shown in a cinematic video released by Isil on Sunday night. After directing the brutal murders for the camera, a khaki-clad militant points a bloodstained finger northward and says: "We will conquer Rome, by Allah's permission."
On Monday, David Cameron condemned the "barbaric" executions and vowed to defeat the "monstrosity" of Islamic extremism.
French president François Hollande and his Egyptian counterpart Abdel Fatah al-Sisi called for the UN security council to meet over Libya and to take new measures.
Three years after the fall of longtime dictator Muammar Gaddafi, UN-brokered peace talks are seen as a last hope for a country spiralling out of control – it has two rival parliaments, each nominally allied to a patchwork of militias, and a power vacuum in which militant groups including Isil are taking root.
The 21 victims of Isil's latest atrocity were all migrant workers who hailed from an impoverished region in central Egypt. They had travelled to Libya hoping to make a new life – day labourers in the oil-rich nation can command salaries of up to six times more than they could make at home.
The captives, all kidnapped from the Libyan city of Sirte in recent months, are the first foreigners killed by Isil outside territory that the group currently controls in Syria and Iraq, in what appeared to be the clearest sign yet of the extremists' growing reach.
Isil called the video depicting the murders "a message signed with blood – to the nation of the cross".
On Monday morning, the dusty back streets of one Egyptian village, Al Our, were filled with the sounds of grief. It had been home to fourteen of the hostages.
Egypt responded to the executions with its first official foreign military operation for two decades, mounting bombing raids against what it described as Isil-linked targets in Libya's coastal city of Derna.
Libyan air force commander Saqr al-Joroushi told Egyptian state television that about 50 militants were killed in the air strikes, which were coordinated with the military of Libya's internationally recognised government. He said his air force had also shelled sites in Sirte and Bin Jawad.
In a statement, Egypt's army said it had targeted 'weapons caches and training camps'. The claims could not be independently verified.
The army said the bombing raids were "to avenge the bloodshed and to seek retribution from the killers".
Egypt has previously provided clandestine support to forces allied to Libya's internationally recognised government, which fled the capital for the eastern cities of Bayda and Tobruk last year.
"Let those far and near know that Egyptians have a shield that protects them," said the Egyptian army statement on Monday.