DAESH has built a base in Libya from which to exploit tribal conflicts and expand across Africa, though experts say the militants remain vulnerable even if the West's attention is elsewhere.

Libya's collapse into a chaotic mess of competing militias, since the overthrow and death of dictator Muammer Gaddafi, has made it an ideal stomping ground for DAESH.

DAESH fighters gradually built up control of several towns that were of minimal interest to other militias, most notably Gaddafi's coastal hometown of Sirte, east of Tripoli.

Libya not only offers an alternative base if the group is forced out of Syria and Iraq, but experts also fear it could take advantage of tribal conflicts to expand south into the Sahel desert region of central Africa, particularly Chad, Niger and Sudan.

"DAESH is provoking tensions and making alliances," particularly between the competing Tuareg and Toubou tribes, said Kader Abderrahim of the Institute of Strategic and International Relations in Paris.

For now, DAESH has a limited foothold in Libya, but it is enough to project violence into neighboring countries, particularly Tunisia where the group has claimed three attacks this year."Tunisia is the most threatened," said Abderrahim. "The terrorists cannot accept the idea of a functioning democracy just a few dozen kilometers away."

Libya also lies just 500 miles across the Mediterranean from Italy, and is a route for thousands of refugees, another weakness DAESH could exploit.

"There is still this old historical fantasy of reconquering the territory they held in Spain... of returning Andalucía to before the Middle Ages," Abderrahim said.

Libya, nonetheless, represents a much less hospitable environment for DAESH than Syria and Iraq.

"Libya without a state is not really a functioning place. DAESH in Libya would be vulnerable to the same problems as the Gaddafi regime - including the need to import 70 percent of its food - and there is a much smaller population from which to extort revenue and taxes," said Geoff Porter, head of the U.S.-based North Africa Risk Consultancy.

Libya's long coastline and desert plains leave DAESH vulnerable to outside attacks, said Frederic Wehrey, a senior associate with the Carnegie Endowment for International Peace who visited several cities there in September.

But as in Syria and Iraq, the problem for the West is finding partners on the ground to fight DAESH.

"The Libyan actors that are capable of confronting DAESH are not really doing so for reasons of capacity, but also of will," Wehrey said. "They are holding the line, but both the main factions have other priorities."

Libya has two governments vying for power - a militia alliance including rebel groups that overran Tripoli in August 2014, and the internationally recognized administration that fled to eastern Libya.

Western efforts have focused on fostering reconciliation between the two sides, hoping they will then turn their firepower on militant groups, but months of U.N.-brokered talks have made little progress.

For now, DAESH has been held in check by the "super-abundance" of armed opponents in the country, Porter said.

It was driven out of the city of Derna in June by an al-Qaida affiliate and is jostling for control in other areas.

"It is not threatening the entire country," added Wehrey. "But it has a beach-head and the human catastrophe of the civil war is fertile ground for them to expand.