General Haftar chose war over talks in a bid to unite the country under his leadership. His prospects for success are uncertain, but the risk to Libya’s vital oil sector is real.

It took Libya’s eastern-based General Khalifa Haftar three years to seize Benghazi from Islamic militants and one year to take Derna in the east. But his recent operation which swept through the sparsely-populated lawless south lasted just two months.

His self-styled ‘Libyan National Army’...