Follow the money. Actually, "Deep Throat" or W Mark Felt Jr of the FBI, as he revealed himself to be, never uttered those words to the Washington Post reporter Bob Woodward. Yet, this has not stopped the best line from the Watergate scandal becoming a leitmotiv for political scandals since. Today, if you want to fathom the curious tensions between Saudi Arabia and Egypt, donor and supplicant, you should also follow the money.

We can now drop the qualification of “alleged” around the contents of hours of secretly-recorded conversations between Abdel Fattah al-Sisi and his inner circle. Sisi’s voice on the tapes has been authenticated by British forensic acoustic experts, who had previously confirmed the voice of Mamdouh Shahin, his military legal advisor.

Among other things, Sisi and his office manager Abbas Kamel revealed the real amount of Gulf money that has been poured into the Egypt army’s bottomless coffers. Saudi Arabia, the United Arab Emirates and Kuwait gave Egypt $39.5bn in cash, loans and oil derivatives between July 2013 (the date of the coup) and January - February 2014. Since then, more money has gone in. Some calculate the up-to-date sum is closer to $50bn.

If you have just inherited the Saudi throne, you might inquire what has happened to all that money, before doling out more. But that is not what has happened. Instead, Sisi has gone on the offensive by putting it about that he is asking the Saudi monarch for more. That is what he told a meeting of high-ranking Egyptian military officers at al-Mazzeh military air force base, east of Cairo. Sisi told them he had “reminded the Saudis of their responsibilities”.

It is also the line one of Sisi’s pet TV anchors was instructed to put out. Amani al-Khayyat broadcast that Sisi had told Salman in his latest meeting: “you will pay the price for your choices”.

This public spat between client state and paymaster is revealing.

Since Salman arrived on the throne, Egypt has received $6bn from the three Gulf States - but I understand that this money is not in cash. It’s a loan to be repaid at 2.5 percent - a rate higher than the International Monetary Fund would charge.

From the word go, Sisi made his decision to oust Mohamed Morsi contingent on the financial support he could extract from Saudi Arabia and other Gulf States. In the months before June 2013, Sisi wavered, and it was only after he got a cast iron commitment from former Saudi King Abdullah that the military coup would get $12bn that Sisi decided to put his plan into action. The coup was many things. But one element of it was a financial proposition. If that is now ending, the bet looks very different for Sisi. Follow the money.

Salman’s attitude to Sisi could be glimpsed in a long session the Saudi monarch had with the Turkish President Recep Tayyip Erdogan. Erdogan had three conditions before he would agree to a public reconciliation with Sisi, who was in Saudi Arabia at the time: that political detainees be released; that the death sentences be annulled; and that Sisi would allow freedom of association, ie the right to demonstrate. As this would undo the three pillars of the military coup, it was obvious that Erdogan’s demands could not be met.

There was in Erdogan’s own public account of the meeting, no meeting of minds on Egypt. Salman said Egypt had always been run by a military dictator. If not Sisi, them whom, he asked the Turkish side at the talks. Saudi Arabia sought only one thing from Egypt and that had nothing to do with the Arab Spring, Tahrir Square, or democracy – they wanted stability. And how could you guarantee stability without the army in charge?

That was Salman’s argument. But this is not the rock solid 100 percent support for Sisi that it appears to be. There is a difference between saying that Riyadh supports stability in Egypt and saying that it supports Sisi. What if another general with the backing of the military were to come forward with a viable plan to normalise the country? How long would Sisi remain the man to support? What if the country became more unstable, not less?

Franklin D Roosevelt replied to the proposition by Sumner Welles, his secretary of state, that the brutal Nicaraguan dictator Somoza was a bastard by saying: “Yes, but he's our bastard." This does not apply to Sisi. The Egyptian dictator is not Salman’s man. Rather, he is one of the many mistakes his half-brother Abdullah made in the twilight years of his reign. Salman should not, and does not, feel responsible for Sisi’s fate, only Egypt’s.

To continue with the logic of the Saudi argument, Sisi’s future depends on proving that he can stabilise Egypt. All the evidence is to the contrary. As the Egyptian political scientist Emad Shahin argues in his recent paper, Sisi’s rule is becoming increasingly personalised in the absence of an elected parliament. He has issued 263 decrees since coming to power. He has not succeeded in forming a political base behind him. Nor can he remove the current defence minister, thanks to the constitution which secured his own former position in that post.

Now that he has taken off his army uniform, Sisi as a civilian president is caught in a web of his own making. The security situation inside Egypt is worsening. The number of recorded acts of political violence in the first three months of this year was 1,641, or one incident every 90 minutes.

Some highly placed figures in the Egyptian military establishment have expressed alarm at this and have spoken of their unease to colleagues in parallel institutions outside the country. They were never happy about the coup in the first place and supported it because they felt there was no other option, and now they increasingly question the path that Sisi is taking them on.

I have been told that one of them reportedly said: “It has never been as bad as this in Egypt.” The conclusion drawn by those listening to them is that cracks are starting to appear in the military.

One can see these generals’ point of view. They don’t think the army can cope with the demands made on them, as it has now become the primary domestic security agency. And they don’t want the army to be held responsible for the social chaos. Possibly this is one of the motivations for taping the conversations of Sisi’s kitchen cabinet and releasing it only two weeks after Salman came to power. As Abbas Kamel’s mobile is provided by the General Intelligence Service, the taping of Sisi’s inner circle was an inside job. Someone wanted Salman to hear first-hand what Sisi is saying and thinking about the Gulf donors on whom he depends.

Of particular concern is the possibility, some say probability, that the insurgency in the Sinai Peninsula could migrate to mainland Egypt. To suppress it, the Egyptian army has resorted to brutal tactics - demolishing the Egyptian half of Rafah, the city that straddles the border with Gaza, imposing curfews, shooting up villages and destroying an estimated 10,000 homes. Sinai has a sparse population - about half a million. What if the same thing starting happening in Upper Egypt which has a population of 30 million?

The region is religiously conservative, it voted overwhelmingly for the Muslim Brotherhood, and it is economically marginalised. It is here that Wilayet Sinai, a franchise of the Islamic State, intends to set up shop. Abu Safyan al-Masri, an IS member from Wilayet Sinai, announced that a branch would soon be opening. Asyut and al-Fayoum, both in Upper Egypt, were noted for harbouring anti-state militancy during the 1990s. An Upper Egypt IS supporter said “violence can be faced only with violence - these organisations cannot sit with their hands tied without responding”.

The announcement was dismissed as “a media event of no value” by General Mohammed Mahfouz, an Egyptian military expert.

“We are different from Syria, Libya and Iraq - our army is still an effective actor, and no [non-state] organisation has control over limited areas as is the case in Syria.”

Mahfouz said that “unfortunately, Egypt’s borders to the east, the west and the south are all linked to states that support the political Salafist tide, or that contain large areas dominated by that tide. Groups exploit gaps in the border to push their agents [into Egypt]”.

We shall see. The Western powers supporting Sisi, and the European Union in particular, cannot afford to see a crisis developing in Egypt and only attempt to step in once it has exploded. It waited for Libya to unravel, Syria to become a civil war, Yemen to do likewise.

If Egypt followed the same path, the explosion would not be on a conventional scale. It would be a nuclear one. Egyptians fleeing it would only have one direction to travel. They would take to the boats northwards to Europe. For how much longer can Europe afford itself the luxury of watching Egypt destabilise?

- David Hearst is editor-in-chief of Middle East Eye. He was chief foreign leader writer of The Guardian, former Associate Foreign Editor, European Editor, Moscow Bureau Chief, European Correspondent, and Ireland Correspondent. He joined The Guardian from The Scotsman, where he was education correspondent.

The views expressed in this article belong to the author and do not necessarily reflect the editorial policy of Middle East Eye.

Photo Credit: Saudi King Salman bin Abdulaziz al-Saud welcoming Egypt's President Abdel Fattah al-Sisi before a meeting on 2 May, 2015 during an official visit in the Saudi capital Riyadh (AFP)