The promotion of Mohammed bin Nayef bin Abdel-Aziz Al Saud to be the new Saudi interior minister has come as a surprise to most Western analysts.
However, it is likely to be welcomed in Western capitals as a sign that a younger generation of Al Saud princes are taking on a greater role in decision-making in a system sometimes described as a gerontocracy, where septuagenarians and octogenarians rule a population that is mostly under thirty. Moreover, Prince Mohammed, who is 53, has strong relations with the US, as does another recently elevated third-generation Al Saud, Prince Bandar bin Sultan bin Abdel-Aziz Al Saud, the new head of intelligence.
Prince Mohammed is one of two prominent sons of the former interior minister and crown prince, Prince Nayef, who passed away earlier this year. He has years of experience working with his father at the interior ministry, but in line with Saudi traditions of respect for family seniority, the post of interior minister initially passed to a more senior member of the family, Prince Ahmad bin Abdel-Aziz Al Saud.
Prince Ahmad, like the king, Abdullah bin Abdel-Aziz Al Saud, is one of the sons of the country's founder, Abdel-Aziz Al Saud, and, at 70, is one of the younger of the surviving sons. No reason was cited for his departure, which was said to have been at his request.
Previously it has been rare to replace a senior prince during their lifetime, though not completely unheard of. In 2009 there was a far less high-profile change of the guard at the ministry of municipal affairs (not strategically vital, but charged with overseeing municipal elections, which are the only state elections that exist in the kingdom) when Prince Mutib bin Abdel-Aziz Al Saud stepped down in favour of his son, Prince Mansour.
More dramatically, in July this year, Prince Bandar, who is 63, replaced another second-generation prince, Prince Muqrin bin Abdel-Aziz Al Saud - who is not much older, being 67, and one of the younger half-brothers of the king, but who was seen as disadvantaged by having a non-Saudi mother - as head of Saudi intelligence. Prince Bandar is a son of Prince Sultan, the longstanding defence minister who died last year, who also preceded Prince Nayef as crown prince (meaning that while the previous two crown princes died before the king, their sons have nonetheless been able to advance further and faster than their third-generation peers). He is an ex-ambassador whose more than two decades in Washington left him with extensive US connections; he is also seen as one of the more hawkish Al Saud when it comes to Iran and Syria (Iranian media carried false claims that he'd been assassinated by Syrian militias in July).
This latest move would seem to increase the likelihood of the royal succession moving to the third generation earlier than many expected.
Prince Ahmad had been seen in the West as the most likely successor to the throne. It was pointed out at a seminar in the UK parliament only last week that in theory, if Prince Ahmad lived as long as King Abdullah has so far, he could still be king in 2017. It is not certain that he is entirely ruled out of the succession, as the reason for his departure hasn't been made clear.
But the promotion of Prince Mohammed suggests Saudi rulers are increasingly aware of the need for new blood - and more energetic younger figures - at the top.
The succession has been seen as one of the main risks to Saudi stability - but at least it is one the royals are conscious of and will be preparing for, even if most of this happens behind closed doors and is frustratingly opaque to the West. In the immediate term, arguably the advanced age of senior decision makers has been more of a concern, as their time and energy has often been limited by health concerns and as the system discourages delegation.
In the West, Prince Mohammed is best known for a programme of rehabilitation he has overseen for suspected Al-Qaeda sympathisers, which has offered a mixture of religious re-education, social re-integration and family-supported co-optation strategies to militants who are not believed to be personally responsible for casualties. Techniques range from having clerics debating the Quran with them to, in some cases, arranging marriages for them on their release.
The programme has been generally quite well regarded as a more hearts-and-minds based approach to counterterrorism than the famously hard line approach of Prince Nayef, who had been at the helm of the interior ministry for the best part of four decades, overseeing the religious police as well as internal security. Western policy makers see Prince Mohammed as a modernizing force.
Nonetheless, the risks of his sometimes conciliatory approach to religious hardliners were made evident in 2009 when a supposedly repentant Al-Qaeda member blew himself up in the prince's home - reportedly a near-miss assassination attempt. As regards the 'jihad rehab' programme, human rights groups have raised concerns about the absence of judicial process, while Saudi liberals - whose support base is probably smaller - wryly note that no such forgiveness and re-integration is on offer to those liberal activists who have been jailed for such crimes as petitioning for a constitutional monarchy.
Prince Mohammed will now be seen as a key contender for the throne in the future. Other prominent princes from his generation include his brother Prince Saud, who heads the court of the crown prince (and defence minister), Salman bin Abdel-Aziz Al Saud; Bandar's brother, Khaled bin Sultan, who is deputy minister of defence and likely to eventually succeed Prince Salman as defence minister; Khaled bin Faisal bin Abdel-Aziz Al Saud, governor of Mecca, son of a former king, Faisal, and brother of the foreign minister; Prince Miteb bin Abdullah bin Abdel-Aziz Al Saud, son of the king and head of the national guard. But the succession will depend critically on private consultations within the family - which has a formal council to help the king decide on the political succession - and thus remains a guessing game for outside observers.