(Bloomberg) — How could Saudi Arabia, a country with the world’s third-largest military budget and six battalions of U.S.-built Patriot missile-defense systems, fail to defend the beating heart of the oil industry on which the kingdom depends?

That question lies at the heart of responses to Saturday’s attack on Abqaiq, which cut Saudi oil production by half, and is critical to any assessment of whether investors will have to permanently factor higher political risk assumptions into the price of oil.

As audacious as the strike was, it was only the latest in a series and should have come as no surprise. The effectiveness of the Saudi military machine has long been questioned, despite spending $83 billion on defense last year, compared to $45 billion for Russia and $20 billion for regional rival Iran. The kingdom’s formidably equipped air force has been bombing Iran-backed Houthi rebels in neighboring Yemen since 2015, but has so far failed to tip the civil war in favor of Saudi allies.

Yet any firm answers to the question of Saudi vulnerability will have to wait for more clarity on exactly what happened on Saturday, according to air defense specialists. There are conflicting accounts as to what technologies were used — a swarm of 10 armed unmanned aerial vehicles, cruise missiles or a mix of the two.

“If it was a mixed attack, if you have small UAVs plus cruise missiles coordinated, coming in at low level — that is a wicked problem to deal with, even for a capable Western military,” according to Douglas Barrie, senior fellow for military aerospace at the International Institute for Strategic Studies, a U.K. think tank. “The best place to stop this stuff is before it gets in the air.”

Formidable Challenge

Defending against drones — whether over airports or on the battlefield — was a hot topic at the U.K.’s biggest annual defense show last week among the companies that manufacture and sell high-end defense systems to governments around the world, said Barrie.

The nature of oil installations — large, stationary and inflammable — in any case makes their defense a formidable challenge, according to Barrie and others. So too their dispersion across Saudi Arabia’s vast empty spaces and the need to monitor thousands of miles of porous borders with Yemen, Oman, United Arab Emirates, Qatar, Kuwait, Iraq and Jordan.

An online comment – All the best weapons in the world will not matter if the troops using them don’t care. Saudi Arabia has a real motivation problem. Troops don’t even bother showing up except for parades.

They should be able to defend the Kingdom against any threat with the weapon systems they own. But that depends on competent weapon system operators and a command structure that cares.