Kuala Lampur, Sept. 15 -- The Houthis are no longer merely demonstrating that they can survive a prolonged war in Yemen.

They are showing that a comparatively small non-state actor, armed with drones, missiles and geographical advantage, can impose increasingly serious costs on the international economy.

The latest attack on Saudi Arabia's East-West oil pipeline should therefore be understood as more than another episode in the seemingly ceaseless violence engulfing West Asia.

It is potentially a systemic shock.

Saudi Arabia could exhaust the oil stocks available for export through the Red Sea within days unless the damaged pipeline can be restarted.

The 1,200-kilometre East-West pipeline, running across the Arabian Peninsula towards...