Saudi Arabia's King Salman made his son his successor on Wednesday, removing his nephew as crown prince and giving the 31-year old almost unprecedented powers as the world's leading oil exporter implements transformational reforms.
A royal decree appointed Mohammed bin Salman crown prince and deputy prime minister. He retains defence, oil and other portfolios.
It said Crown Prince Mohammed bin Nayef, a counter-terrorism chief admired in Washington for putting down an al-Qaeda campaign of bombings in 2003-06, was relieved of all positions.
Although Mohammed bin Salman's promotion was expected among close circles it came as a surprise at a time the kingdom is facing heightened tensions with Qatar and Iran and is locked in a war in Yemen.
#BREAKING：Saudi King replaces #MohammadBinNayef with #MohammadBinSalman as crown prince -- reports pic.twitter.com/vJyr1T4I4y — China Xinhua News (@XHNews) June 21, 2017
Analysts said the change ends uncertainty over succession and empowers Prince Mohammed bin Salman to move faster with his plan to reduce the kingdom's dependance on oil, which includes the partial privatisation of state oil company Aramco.
Bernard Haykel, professor of Near Eastern Studies at Princeton, said the king's decision was aimed at avoiding a power struggle between his son and Mohammed bin Nayef by setting the line of succession clearly.
"Some people were predicting that this would lead to a division in the family and strife and some kind of revolt. I don't see that happening."
A senior Saudi official said the decision was taken due to what he called special circumstances presented to the members of the Allegiance Council. He added that Mohammed bin Nayef supported the decision in a letter sent to the king.
The royal decree did not nominate a new deputy crown prince. The position is relatively new in Saudi Arabia where a king has traditionally chosen his own successor.
As deputy crown prince, Mohammed bin Salman has been responsible for running Saudi Arabia's war in Yemen, dictating an energy policy with global implications and spearheading plans for the kingdom to build an economic future after oil.
That the royal succession in the world's top oil exporter is closely scrutinised only makes the rapidity of Mohammed bin Salman's rise to power, and the speed with which his better known cousins were brushed aside, more astonishing.
HUGE: king Salman dismisses Crown Prince Mohammad bin Naif & appoints his son Mohammad bin Salman in his place. #SaudiArabia (1) pic.twitter.com/muWnubbJc3 — Dr. Abbas Kadhim (@DrAbbasKadhim) June 21, 2017
Outside Saudi Arabia, that rapid advance and the sudden changes to longstanding policies on regional affairs, energy and its economy have prompted unease, adding an unpredictable edge to a kingdom that allies long regarded as a known quantity.
Inside, they have prompted admiration among many younger Saudis who regard his ascent as evidence that their generation is taking a central place in running a country whose patriarchal traditions have for decades made power the province of the old.
Iran, Saudi Arabia's maain rival for regional influence, called Prince Mohammed's appointment a "soft coup".