RIYADH — Saudi Arabia has deep pockets and cutting-edge weapons yet for more than a decade it has been unable to quash Yemen’s battle-hardened Houthis.

The Iran-backed group has now attacked Riyadh with a missile strike, seized Yemen’s entire Red Sea coast and is blockading Saudi oil exports, seemingly unimpeded.

Experts say Saudi Arabia has struggled to rebuff the group in part due to its reliance on ineffective proxies on the ground, while rugged terrain and Iranian support have favoured the Houthis.

The kingdom has spent billions acquiring sophisticated weaponry and military kit, while historically relying on a large presence of foreign personnel, contractors and trainers to supplement its forces.

Major weapons purchases from Western manufactures — including American, British and French companies — have become a defining feature of Saudi defence policy and diplomatic strategy to curry favour with its allies.

Last week, the United States has approved a $24.3 billion sale of 48 F-35 stealth warplanes to Saudi Arabia.

Despite its formidable arsenal, the Saudi military has had relatively limited experience overseeing complex combat operations on its own.

“The Saudis have to build a military that’s willing to fight and a population that’s willing to die to preserve what they have,” said Bernard Haykel, a Saudi expert at Princeton University, during a discussion posted online after the Houthi’s latest offensive.

“And that’s not what they have right now.”

Experts have long suggested that the kingdom’s military forces have purposely remained smaller and fragmented to prevent a putsch in a region prone to coups.

“Saudi Arabia is the one place where the monarchy has not [been] displaced by [the] military, because they have kept the military weak,” Middle East scholar Ray Takeyh told a congressional hearing in 2015.