Bahrain's move to formally establish relations with Israel could not have happened without Saudi Arabia's green light, another step in what observers call Riyadh's "alternative normalisation" of ties with the Jewish state.

Bahrain on Friday became Saudi Arabia's second Gulf ally to announce plans to formalise relations with Israel over the past month, after the United Arab Emirates' landmark agreement.

The move put a spotlight on the potential role of Riyadh, which has so far fended off pressure from US President Donald Trump to follow suit.

The development, billed by Trump as "truly historic", was unlikely to have happened without the silent endorsement of Riyadh, which holds enormous leverage over Bahrain.

Saudi Arabia, the Arab world's biggest economy, was among the Gulf powers that pledged $10 billion in financial aid in 2018 to cash-strapped Bahrain, and it sent troops in 2011 to shore up the ruling family following an Arab Spring uprising.

"I trust that the kingdom of Bahrain consulted with the Saudis on this decision out of respect for them," Marc Schneier, an American rabbi who is an advisor to Bahrain's king, told AFP.

"The Bahrain government has been very respectful of the Saudi position throughout this process."

Saudi officials have publicly remained tight-lipped over the development, but a source close to the establishment hinted it was a concession to Trump after he exerted enormous pressure on Riyadh to form diplomatic ties with Israel.

"You're going to have quite a few countries come in, the big ones are going to be coming in. I spoke to the king of Saudi Arabia... we just started the dialogue" about normalisation with Israel, Trump told reporters this week after a telephone call with King Salman.

Saudi state media did not address the subject in its readout of the call, only quoting the king voicing support for a "lasting and fair" solution to the Palestinian issue. 

Below the radar 

Saudi Arabia, home to Islam's holiest sites, is unlikely to make a similar deal with Israel immediately, as doing so without a resolution to the Palestinian issue would be seen as a betrayal of the cause and hurt its image as the leader of the Muslim world.

And analysts say it does not feel a pressing need to after having cultivated covert ties with Israel, which it views as a bulwark against its regional nemesis Iran, even as it has voiced steadfast support for an independent Palestinian state.

Earlier this month, Saudi Arabia agreed to permit UAE flights to Israel to overfly its territory, in another concrete sign of the kingdom's cooperation with the Jewish state.

"This is what I would call 'alternative normalisation'," Ryan Bohl, of the US geopolitical think tank Stratfor, told AFP.

"Though Saudi will remain slower on this path, it's clear the kingdom is open to normalisation and will explore growth in the relationship through increasingly public, though likely indirect, ties."

'Testing ground' 

Despite its public stance, the pro-government Saudi media has repeatedly tested public reaction by publishing reports advocating closer ties with Israel.

Earlier this month, a preacher in the holy city of Mecca triggered a social media storm when videos of his sermon surfaced that showed him speaking of what he called Prophet Mohammed's outreach to people of other faiths, particularly Jews.

The sermon by Abdulrahman al-Sudais, who courted controversy in the past over his anti-Semitic views, was interpreted by many as a call for normalisation of ties with Israel. 

Riyadh will explore indirect relations with Israel until the "Saudi public is better prepared for a deeper strategic change", Bohl said.

Saudi Arabia is mindful that, like some other Gulf states, its population too may be highly sympathetic to the Palestinian cause.

After a relatively muted public reaction in the UAE, dissidents in Bahrain, which is Sunni-ruled but has a large Shiite Muslim population, rejected the government's move to establish relations with Israel as a "betrayal".

Saudi Arabia will be closely watching the public reaction in Bahrain, which unlike other Gulf states has a long history of civil society movements, even if they have been suppressed since the Arab Spring. 

"Saudi Arabia often uses Bahrain as a testing ground for its future policies," Kristin Diwan of the Arab Gulf States Institute in Washington told AFP.

"But then Saudi Arabia's calculations for normalising relations with Israel are genuinely distinctive from those of a small littoral Gulf state without the religious heft and responsibility of the kingdom."