Dec. 8, 2016 7:38 p.m. ET  American-backed Libyan forces this week expelled Islamic State from the coastal city of Sirte, depriving the jihadist army of its main urban stronghold in the country. That’s news worth celebrating, even if the jihadist threat to Libya is far from contained.  The capture of the city was the culmination of a campaign launched this spring by militias based in the city of Misrata, another coastal town about 100 miles to west of Sirte. As with Kurdish and Iraqi operations against Islamic State earlier this year, American air...  American-backed Libyan forces this week expelled Islamic State from the coastal city of Sirte, depriving the jihadist army of its main urban stronghold in the country. That’s news worth celebrating, even if the jihadist threat to Libya is far from contained.  The capture of the city was the culmination of a campaign launched this spring by militias based in the city of Misrata, another coastal town about 100 miles to west of Sirte. As with Kurdish and Iraqi operations against Islamic State earlier this year, American air power proved decisive, with the U.S. flying almost 500 sorties against Islamic State positions in Libya.  The victory will make it harder for Islamic State to gather Libyan oil revenues, launch naval operations elsewhere in the country, or attempt to infiltrate Europe from Libya. Yet it will continue to menace Libya as well as neighboring Egypt and Tunisia.  Some 2,500 Islamic State fighters escaped the city before it fell to Libyan forces, and the risk is that many will melt into the civilian population or try to occupy rural areas further inland. Per the usual Islamic State modus operandi, what remains of Sirte is rigged with mines and improvised explosive devices, meaning it will take months if not years for normal civilian life to resume.  The bigger worry is that, with Islamic State out of Sirte, Libya’s competing militias will escalate their own civil war. The forces that captured Sirte for the most part flew the flag of the U.N.-recognized Government of National Accord (GNA) that was formed late last year. Yet Libya’s political landscape remains a patchwork of competing nationalist, tribal and Islamist militias that are at war with each other and that don’t fully recognize the GNA, if they do at all.  Western governments have an interest in ensuring that Islamic State doesn’t return in force to Libya’s oil-rich coastal areas, which is why airborne vigilance and special-forces assistance must remain on the agenda of the incoming Trump Administration. But it also means the West will have little choice but to help the Libyan state govern itself, lest endless civil war give Islamic State further opportunities to thrive amid the chaos.
Islamic State loses its Libyan stronghold of Sirte, but it can always come back, says an editorial in The Wall Street Journal.