Saudi Arabia is a crucial ally of the United States within the Middle East, but the long-time friendship between the two countries may now be under pressure.
Diplomatic sources say that Prince Bandar bin Sultan, Saudi's intelligence chief, has been talking about his country making a "major shift" in its relationship with the US.
He has been quoted as sharply criticising US policies on Syria and Iran, as well as condemning its apparent lack of urgency on the Palestinian-Israeli track.
The deepening rift was acknowledged by US Secretary of State John Kerry. Speaking to reporters in London on Wednesday he said:
I don’t think there is [a dispute between the two] … because I am judging with what has taken place yesterday in London between Saud al-Faisal, the Saudi foreign minister, and John Kerry the Secretary of State from the US. There was a mature understanding, a joint communication agreement on what needs to be done vis-à-vis Syria, no comments … [were made] to give this story any credibility as far as the Saudi government is concerned, so I am not going to give the story credibility.
"We know that the Saudis were obviously disappointed that the Syria strike didn't take place. It is our obligation to work closely with them – as I am doing ... [but] I think there is a clear understanding in our relationship going forward, and I have great confidence that the United States and Saudi Arabia will continue to be the close and important friends and allies that we have been."
But why is the kingdom apparently reassessing its relations with the US?
Going back to 2011, the Saudis were then angered by US criticism of the crackdown on anti-government protests in Bahrain. The government was also upset about the lack of US military action against Syria.
Saudi Arabia cancelled a speech at the UN General Assembly last month, and recently rejected a seat on the Security Council, citing "international double standards" on the Middle East as the reason.
The recent warming of relations between the US and Iran has also outraged the kingdom.
Saudi Arabia is seen as a pivotal anchor to US interests in the Middle East, and for decades the two have nutured ties primarily based on mutual oil and security interests.
Historians refer to a meeting between King Abdel Aziz and President Franklin D Roosevelt in 1945 as securing what is called "the special relationship". That relationship continued throughout the Cold War with Saudi Arabia backing the US fight against communism.
Saudi Arabia's 1973 oil embargo on the US put a strain on the relationship. But the kingdom later stepped in to fill the global oil shortage when war broke out between its neighbours Iraq and Iran - a policy that was co-ordinated with the US.
More recently, the 9/11 attack, and the fact that many of the attackers were of Saudi origin, seriously damaged the kingdom's image in the US. However, shared concerns about armed groups like al-Qaeda, and Iran's regional ambitions, have provided what has been called a "renewed logic" for their strategic partnership.
The kingdom holds hundreds of billions of dollars in US treasury bonds; American oil and construction contractors have a massive presence in the kingdom; and Saudi also buys the bulk of its military equipment from the United States. The latest deal, posted on the Pentagon's website just a few weeks ago, is worth $7bn.
So, is this a mere spat between the two countries, or the beginning of the end of a special relationship? And what will be the regional implications of a distance between them?
To discuss this, Inside Story, with presenter Mike Hanna, is joined by guests: Richard Murphy, a former US ambassador to Syria and Saudi Arabia; Hussein Shobokshi, a columnist at Asharq Alawsat, an international Arabic newspaper; and Greg Gause, professor of political science at the University of Vermont, who is also the author of Saudi Arabia in the New Middle East.
"I do think that there are real differences and opinions … on important issues like Syria and Egypt, [but] I do [also] think that the core of the relationship, which is always been about security in the Gulf region, is still there and still intact … Saudi is worried about the American talks with Iran, but I think that some of those fears are exaggerated, I don’t think that the United States is going to be turning over the keys of [the] Gulf security to Iran anytime soon."
- Greg Gause, a professor of political science at the University of Vermont