By Angus McDowall
RIYADH (Reuters) - Changes in Saudi Arabia's leadership have concentrated power in an inner circle of the Al Saud dynasty, removing constraints on the monarch and making the conservative kingdom's strategic positions less predictable.
The world's top oil exporter has always prized stability, developing policies slowly and altering them rarely, partly because of the need to balance rivalries among ruling family members and their conflicting interests.
That may now be changing. Since inheriting the throne from his brother in January, King Salman has embarked on a war in neighboring Yemen, restructured the oil sector and shaken up domestic governance, including the line of succession.
Whether this is the beginning of a much more assertive foreign policy aimed at countering rival Iran, a new energy strategy or a more authoritarian security approach, as analysts have speculated, remains unclear.
But what is increasingly apparent is that Riyadh's new rulers enjoy more scope to make dramatic and unexpected interventions than their predecessors did.
"If the king wants, for example, to send ground troops to Yemen, he doesn't have to call the whole family to do that any more," said Jamal Khashoggi, general manager of television station al-Arab.
While the monarch has always had the last word in policy decisions, he has usually had to win consensus among a group of powerful princes, often his own brothers, for any big changes.
That no longer appears to be the case, as a growing number of offices are absorbed into the hands of a new triumvirate of the king and his two heirs, his nephew Crown Prince Mohammed bin Nayef and his son Deputy Crown Prince Mohammed bin Salman.
"If you look at the two princes, they are controlling the state under the supervision of the king," said Khalid al-Dakhil, a Saudi political scientist.
Salman will be the last son of the kingdom's founder Abdulaziz to rule Saudi Arabia, following five older brothers who were each constrained by important siblings who had built up independent power bases in the administration or armed forces.
He is the last of a group of princes who established their credentials as part of the ruling elite in the early 1960s by backing the winning side in an internal power struggle, and who collectively dominated for the past five decades.
While several of Abdulaziz's 35 sons survive besides Salman, those who have held senior positions have been sidelined by age or as part of the monarch's recent changes, including his youngest brother, Muqrin, who was removed as crown prince.
Crown Prince Mohammed bin Nayef, already Interior Minister, now heads a super-committee that decides on big security and political issues, while Deputy Crown Prince Mohammed bin Salman is Defence Minister and head of a committee on the economy and development.
The only strategic entity held by a prince from another faction is the National Guard, an elite military unit headed by the late King Abdullah's son Miteb, although other ruling family members serve as provincial governors.
Unlike under previous kings, the intelligence agency and foreign ministry are controlled by commoners beholden to royal patrons, and in strategic government departments like defense and interior, no deputy ministers are princes.
A further sign of growing consolidation came with last week's decision to split state energy company Aramco from the Oil Ministry, a move that could improve the prospects of another of Salman's sons, Abdulaziz, becoming minister.
At the same time, Aramco was given a new supreme council headed by Prince Mohammed bin Salman, making him the first Al Saud member to directly oversee the world's biggest oil company, which has historically been kept away from royal politics.
Some analysts have speculated that the changes represent a final victory for the Sudairi branch of the ruling family, the descendents of seven sons of Abdulaziz born to his favorite wife, including both Salman and the crown prince's father Nayef.
But it is far from clear whether the ties that for decades united brothers whose place in the succession was clear will survive their own deaths and continue to bind cousins who might regard each other as rivals rather than partners.
The five other Sudairi branches do not feature in the new dispensation. Instead, power appears to be consolidated among the individuals who are named in the line of succession and who control strategic departments.
That appears to put the levers of government in the hands of Mohammed bin Nayef, 55, and his 30-year-old cousin Mohammed bin Salman. One other consequence of a more concentrated power structure, however, is that the succession is less predictable.
King Salman got rid of an heir chosen for him by his predecessor. There are no guarantees that Mohammed bin Nayef will not eventually do the same.
(Editing by Catherine Evans)