When Islamic State militants attacked a perimeter gate guarding Libya’s Es Sider oil terminal this month, they sent gunmen to kill guards before attempting to detonate a car bomb in a bid to breach the port’s defenses.

The assault failed to get closer than a mile (1.6 km) from one of Libya’s major oil ports, but it signaled Islamic State’s intent to expand beyond their base in the city of Sirte and target the OPEC state’s oil infrastructure.

Four years after the fall of leader Muammar Gaddafi, Libya is in a conflict with two rival governments each backed by competing armed factions, creating a power vacuum that has allowed Islamic State to establish a foothold in North Africa. […]