whose organisers were people injured during the Arab Spring which overthrew veteran president Hosni Mubarak

"For King Abdullah, the Mubarak episode was just the worst possible nightmare," Crowley cited Martin Indyk, who served as the US Special Envoy for Israeli-Palestinian negotiations from 2013 to 2014, as saying.

Obama's willingness to cooperate with Egypt's first Islamist president Mohamed Morsi added fuel to the fire. The Saudis view the Muslim brotherhood as a terrorist organization.

In November 2013, Riyadh found out that the Obama administration had been engaged in the months-long talks with Saudi Arabia's main adversary, Iran.

"The Saudis opposed the Iran talks on substance – fearing that Obama was planning a strategic shift that would align the US with Tehran and phase out Riyadh as Washington's main strategic partner in the region– but also on process grounds, furious that Obama had, in effect, gone behind their back to negotiate with Iran in secret," Crowley explained.

Last year, King Salman opted not to take part in the summit of the Sunni Arab leaders, held at Camp David.

Crowley pointed out that despite the cold spell both sides are trying to keep the bilateral relationship afloat. Obama backed the Saudi-led campaign in Yemen. Both Washington and Riyadh are trying to overthrow Syrian President Bashar al-Assad. US officials have offered muted responses to the execution of a prominent Shiite cleric Nimr al-Nimr.

"But many observers fear the relationship could grow worse still, with dangerous consequences for the region," he asserted.

I don't see it fracturing at all. It's a relationship that has served powerful US families