Salman fishing in the Yemen

As the Saudi-led aerial war against Yemen's Houthis drags on, with civilian casualties mounting and another ceasefire already broken by both sides, frustrations are reportedly growing in the Saudi capital, Riyadh.

Senior princes in the House of Saud are said to be questioning the wisdom of the bombing campaign, launched in March with such enthusiasm by King Salman's favoured son, Mohammed bin Salman.

The intention of the campaign was to break the back of the Houthi revolt and to re-establish the presidency of Abdrabbuh Mansour Hadi. The Saudi-backed Hadi had rather ignominiously fled by boat, as rebel forces - who had already chased him from the capital, Sanaa - closed in on the southern port city of Aden.

The campaign was also a bold bid by Mohammed bin Salman, or MbS as he is known, to burnish his credentials.

He represents the new breed of Gulf princes, leading aggressively from the front - and not particularly bothered by what allies in the West may think.

His appointment as deputy crown prince in January had already ruffled a few feathers within the ruling family. Then he was announced as defence minister, the world's youngest at 28 (or 32, estimates vary). What better way to enhance his reputation than to administer a sharp, succinct defeat to the Houthis?

Not according to plan

Four months in, the Houthis remain defiantly in place, still in control of Sanaa. True, a pushback begun on 15 July by Saudi-trained forces loyal to Hadi has secured much of Aden, including the airport.

If those troops are able to hold and expand their ground, the stalemate may be broken and the pressure on the Saudis will ease.

Nonetheless, the Houthis have proven to be a tough and wily fighting force. They have already engaged in several border skirmishes with Saudi forces, an uncomfortable reminder to the House of Saud of a disastrous 2009 campaign - one that ended only when Saudi Arabia paid the Houthis a substantial amount of money to withdraw from territory they had seized inside the kingdom.

Senior princes in the House of Saud are said to be questioning the wisdom of the bombing campaign

With still no end in sight and no apparent exit strategy, well placed sources have told al-Araby that very senior princes are frustrated and angry with MbS - referring to him privately as "the boy" or "the teenager".

He is seen as headstrong, overly ambitious, arrogant and "out of control". But they are wary. They need to be - the young prince wields enormous power.

Family fortunes

Among those said to be upset with MbS are some of the surviving sons of Abdulaziz, the founder of the kingdom.

They were passed over when Salman came to power and appointed the powerful interior minister Mohammed bin Nayef crown prince and his son deputy crown prince.

Significantly in a country where appearances count, at least six of the sons of Abdulaziz did not make walaa, that is to pledge allegiance, to MbS when he was installed as deputy crown prince.

Now, my sources say, two of those sons - Ahmed, born in 1942, and Talal, born in 1931 - are among some of MbS' harshest critics, albeit in private.

Someone else who was passed over is Miteb, the son of the late King Abdullah. He is the commander of the 100,000-strong Saudi National Guard, a force whose first allegiance is to the ruling family.

Miteb, disgruntled though he may be, is unlikely to use the national guard as a kingmaker unless the position of Mohammed bin Salman becomes very precarious.

Is that likely to happen? The sources have told me that what they called "serious discussions" between some of the senior princes are already taking place. Concerns about the nuclear deal with Iran has further exacerbated their anxiety.

Geopolitical games

A lifting of sanctions means Iran can sell its oil openly on the world market. Some of the proceeds, the princes fear, will go toward rearming the Houthis, thus prolonging the war and potentially threatening the kingdom directly.

One possible scenario would see MbS being forced to step down as defence minister if his Yemen adventure threatens a Saudi humiliation. That may be a long time coming, though, if at all.

Saudi Arabia remains steadfast in its belief that it can bomb the Houthis to the negotiation table and remain defiant in the face of international concern at the humanitarian disaster unfolding in Yemen.

Observing all of this is Mohammed bin Nayef (MbN). A source with contacts in the interior ministry told me that MbN is paying the price for throwing in his lot with Mohammed bin Salman in order to secure the choice post of crown prince.

There is a possibility that a palace coup may occur, one that would depose the ailing king

"His uncles [Ahmed and Talal] won't help him. He burnt his bridges with them," the source said.

He added that Mohammed bin Nayef was "keeping his head down and trying to avoid irritating Mohammed bin Salman". The prize at stake for both men is the throne itself.

MbN's only hope, the source claimed, is that King Salman, who is reportedly suffering from dementia, will die soon - thus enabling him to become king, while Mohammed bin Salman is hampered by the war in Yemen.

However, King Salman reportedly remains in robust physical health.

The plot thickens

Of course, the insecurities and behind-the-scenes feuding in the House of Saud reflect a larger anxiety about regional instability and the growing strength of Iran.

Should those insecurities continue to rise, the source told me, there is a possibility that a palace coup may occur, one that would depose the ailing king, force out both Mohammeds and install a surviving but competent son of the founding king as a caretaker - while a new order is sorted out.

It is fair to say that similar stories of palace intrigue have swirled for decades around the near impenetrable court of a ruling family whose demise was first predicted more than 50 years ago and has yet to happen.

And removing the king and his two most powerful princes would be a very extreme step indeed.

But what gives the reports of serious family rifts some credence is the war in Yemen, which has thus far only served to create grave instability on the kingdom's doorstep.

And while the Saudis and their allies are busy attacking the Houthis, al-Qaeda grows in strength in the south of Yemen.

Meanwhile, the so-called Islamic State group is a constant existential threat, thriving in the chaos that now defines much of the Middle East.

Never before has the kingdom found itself simultaneously facing two such enemies. With the Saudis fixating on the bombing campaign, neither is being effectively confronted.

The people of Yemen, in the meantime, caught between the Houthis on the ground and the Saudis and their allies in the air are in the middle of what the UN has called a "massive humanitarian crisis" that has left more than 1,500 civilians dead, 3,600 injured and one million displaced.

That is the appalling price ordinary Yemenis are being forced to pay, as Saudi princes play out their extraordinary political games in Riyadh.

Bill Law is a former BBC Gulf analyst. Follow him on Twitter: @Billlaw49

Opinions expressed in this article remain those of the author and do not necessarily represent those of al-Araby al-Jadeed, its editorial board or staff.