Now the US has Isil in Libya firmly in its sights as a target
The American warplanes came around dawn, striking a farmhouse near Sabratha, a picturesque coastal town which is home to some of Libya's most renowned classical ruins. In recent years, however, Sabratha's Unesco-recognised sites have been considered off limits by foreigners due to extremist camps that had sprung up around the town.
Over the last year, Isil had built a presence in Sabratha's hinterland, with many Tunisian militants coalescing there. The US airstrikes yesterday morning targeted a senior Tunisian operative named Noureddine Chouchane. He is believed to have been involved in organising two attacks in his home country last year, including one in the coastal resort of Sousse which claimed the lives of 38 people, including three Irish tourists.
The air strikes yesterday reportedly killed more than 30 Isil fighters at the compound, most of them believed to be Tunisian. It is still not clear whether Chouchane was among the dead.
The bombings were the third publicly acknowledged strikes carried out by the US against extremists in Libya over the past year. Late last summer, US warplanes targeted al-Qa'ida-linked militants in the eastern town of Ajdabiya. Months later, the Americans swooped on Isil sites around the town of Derna, later claiming to have killed Abu Nabil, an Iraqi who was a senior figure in the group's Libyan affiliate.
These latest strikes by the US come as the drumbeats of a possible broader intervention against Isil in Libya have grown increasingly loud in certain Western capitals.
President Barack Obama had recently tasked security advisers to weigh up options, including an expanded aerial campaign accompanied by special forces operations on the ground.
US and European special forces have been inside Libya for months, carrying out reconnaissance work and trying to identify possible targets.
Earlier this month, Italy's defence minister declared that the West could not afford to allow spring to come and go without taking action. French officials have echoed this.
But others have been more cautious, arguing that a UN-brokered unity government that is currently taking shape needs to establish itself first. They say any intervention against Isil should have the imprimatur of the Libyan authorities.
Patience is wearing thin in some Western capitals, however, as Libyan political squabbling delays the formation of such a government.
Yesterday's air strikes show that some Western powers consider the threat from Isil to be such that tackling it takes priority over the twists and turns of Libya's fragile political process.
Estimates vary as to the number of Isil fighters in Libya. Earlier this month, the Pentagon said it believed Isil's strength in Libya amounted to over 6,000 militants.
Hundreds of Libyans went to fight in Syria in recent years and many of them joined Isil there, later returning home to help set up affiliates. The group also includes a large cohort of foreigners, including at leadership level.
The first Isil affiliate in Libya declared itself in late 2014 in the eastern town of Derna. Last year, they were routed from the town by a mix of local Islamist militias and residents.
Isil's stronghold in Libya is the coastal town of Sirte, which was Muammar Ghadaffi's hometown.
After taking over a number of institutions there last year, Isil has consolidated control, snuffing out an attempted uprising and carrying out public executions.
It also abducted and later beheaded 21 Egyptian Copts near the town last year.
Since the beginning of this year, Libya has experienced an unprecedented wave of attacks by Isil. Fanning eastwards from their base in Sirte, their fighters mounted a series of raids on facilities in Libya's oil crescent last month, setting tanks alight in what the National Oil Corporation described as an environmental catastrophe.
While they were eventually repelled by local militias, the attacks indicate Isil's determination to disrupt Libya's hydrocarbons sector, if not seize control of its infrastructure. Also in January, Isil carried out a suicide truck bombing which killed over 60 people at a police training centre in the western town of Zliten - by far the bloodiest attack Libya has witnessed since 2011.
It is no coincidence that Isil's ramping up of activity is happening at the same time that the UN-brokered unity government is struggling to get up and running.
Since summer 2014, Libya has been locked in a political power struggle that has divided the country between rival administrations and parliaments.
The ensuing security vacuum has created an ideal space for Isil to grow. Libya's political factions have so far appeared to be more interested in prevailing over their opponents than taking on Isil.
The US strikes on Sabratha yesterday indicate that Washington feels that it can no longer wait for the Libyans to finally get their act together.