Libya’s oil output of 1.2mn b/d in April was its highest in six months, but this could prove to be the calm before the storm. Eastern-based General Khalifa Haftar’s push to take Tripoli is increasingly calling into question the sustainability of the oil and gas flows vital to the war-torn country’s economy.

Things haven’t exactly gone to plan for the 75-year-old commander of the self-styled Libyan National Army (LNA). Mr Haftar’s operation to...