Saudi King Salman’s elevation of his favourite son, Mohammed, to the post of crown prince was on the cards as soon as the duo took over in January 2015.
This appointment is a departure from Saudi practice. The throne has not previously passed from a son of Abdel Aziz ibn Saud, founder of the kingdom, directly to a son. Mohammed bin Salman will be the first of Abdel Aziz's grandsons to become king.
Mohammed bin Nayef, son of a brother of Salman, was fired as crown prince and interior minister. A powerful figure credited with suppressing religious extremism, he accepted demotion and promptly swore loyalty to his young cousin, a demand made of all senior princes.
They are expected to toe the line as the kingdom is facing multiple challenges: Iran's re-emergence as a regional power; the fall of the price of oil, Riyadh's main source of revenue; the rise of radical fundamentalists; wars in Syria and Yemen; and a rift with Qatar.
The palace coup embraced millennial generation grandsons of the founder. Another key appointment announced on Wednesday was that of of Abdel Aziz bin Saud bin Nayef (34), who was chosen to succeed his uncle as interior minister. Eight other princes representing other branches of the family were given posts to discourage opposition.
Mohammed bin Salman, a lawyer educated in the kingdom, was unknown before his appointment as deputy crown prince and defence minister in January 2015. He soon assumed control of Saudi Arabia’s economic and foreign policies.
On the military front, in March 2015, he launched a war on Yemeni Houthi rebels in the expectation of an early victory. The war is stalemated and Yemen is in ruins. At the same time, he stepped up provision of arms and funds to insurgents in Syria, helping them to reverse gains made by government forces.
Russia intervened the following September, turned the tables on Saudi surrogates, and enabled Damascus to regain lost territory.
On the domestic front, the crown prince has put forward a plan, Vision 2030, to restructure and diversify the Saudi economy. To cut costs, he reduced salaries and pensions of civil servants. Following protests, the king restored both.
The crown prince promised to change Saudi regressive social policies, particularly those impacting on women, but nothing has changed so far due to opposition from the ultra-conservative clerics.
In regional affairs, he has attempted to assert Saudi hegemony over the Gulf and to build a coalition to counter Shia Iran, seen by Sunni Saudis as their chief rival for power. To this end, he orchestrated the high-profile visit of US president Donald Trump to Riyadh, where he called on Muslims to campaign against "terrorism" without elucidating a strategy.
Mohammed bin Salman's pursuit of his goals has antagonised members of the Saudi-dominated Gulf Co-operation Council (GCC) and divided the organisation. He and equally ambitious Abu Dhabi crown prince Mohamed bin Zayed have isolated and blockaded Qatar, accusing the emirate of being a major financier of "terrorism" to deflect attention from Saudi Arabia's role in creating, funding and arming radical fundamentalists fighting in Syria and Iraq and elsewhere.