RIYADH (AFP) - When Saudi Arabia's King Abdullah died a year ago, his subjects expected their country to keep a steady course under new King Salman.
But they were in for a royal shock.
Within hours of acceding to the throne, King Salman, then 79, named his son Mohammed bin Salman, who was not yet 30, as defence minister, setting in motion a year of change while sticking firmly to the Islamic kingdom's conservative foundations.
It was Prince Mohammed, as much as Salman himself, who became the face of the monarchy presiding over one surprise after another during a tumultuous 12 months.
The world's major Sunni power adopted a more assertive foreign policy, began austerity measures to address a record budget deficit, confronted increasing violence from militants and faced heightened global concern over its human rights record.
"The key shift, I'd say, is the more assertive foreign policy," said Dr Adam Baron, a visiting fellow at the European Council on Foreign Relations.
"We've seen the Saudis take a much stronger leadership role in the region, spurred both by feelings of an increased power vacuum and their anxieties over Iran's influence."
The September death of about 2,300 foreign pilgrims during a hajj stampede in Western Saudi Arabia only added to tensions with Shi'ite Iran, which claimed hundreds of victims.
Three months after taking office from the cautious reformer Abdullah, King Salman ruptured with the past and ensured a shift to a younger generation of rulers.
He named a new heir in Crown Prince Mohammed bin Nayef, 56, while Mohammed bin Salman became Deputy Crown Prince and second in line to the throne.
The kingdom also got a more youthful foreign minister with Mr Adel al-Jubeir, 53.
This generational shift was positive, said Ms Iman Fallata, 46, a founder of the Baladi Initiative, which helped prepare women to participate for the first time in municipal elections last December.
"The mentality of the people who govern changed a lot," she said, with younger leaders now in "front position".
Such an endorsement reflects an administration "very in tune with what the Saudi population want," a Western diplomat said.
"And they care about that more than what the West wants or what the liberal elite wants." Yet, despite the generational shift, "they're not trying to push social change in the way that King Abdullah was," said the diplomat.
Saudi Arabia remains one of the most restrictive countries in the world for women.
The dark-bearded Mohammed bin Salman, now 30, holds extraordinary power with multiple portfolios, including as head of a new body overseeing Saudi Aramco, the state oil giant that could be partly sold off in a share offer under reforms forced by the collapse in global crude prices.
Diplomats and analysts have noted an emerging power struggle between Prince Mohammed bin Salman and Mr Mohammed bin Nayef, the interior minister who supervises the kingdom's battle against the Islamic State in Iraq and Syria (ISIS).
The militants have killed minority Shi'ites and police since late 2014.
Ending what the Arab News daily called the kingdom's "customary quiet diplomacy", Saudi Arabia formed an Arab coalition which in March began air strikes against Iran-backed Zaidi Shi'ite rebels who took over much of Yemen.
"The effects of the ongoing military intervention in the kingdom's southern neighbour will continue to shape the Arabian Peninsula for years if not decades," Dr Baron said.
Yemen is one of many Middle East countries where Saudi Arabia sees Iranian interference, which it decided to confront while it perceives a lack of engagement from its traditional ally Washington.
"The United States must realise that they are the number one in the world and they have to act like it," Prince Mohammed bin Salman said in a Jan 7 interview with The Economist.
According to a foreign diplomat, the Saudis "feel isolated and abandoned by a longtime friend".
Those feelings crystallised with Washington's support for a historic agreement that took effect on Saturday between Teheran and major world powers. In return for restrictions on its nuclear capabilities the deal lifts crippling sanctions on Teheran.
Seeing an emboldened Iran, the Saudis acted.
Months of effort led to an unprecedented December meeting by Syrian political and armed opposition factions in Riyadh, a bid for unity before peace negotiations sought with President Bashar al-Assad's Iran-supported regime.
Five days after those Syrian talks, Prince Mohammed bin Salman made the surprising announcement of a 34-member coalition to fight "terrorism" in the Islamic world.
"You can see how we became very strong," Ms Iman Fallata said, following Riyadh's severing this month of diplomatic ties with Teheran after protesters burned its diplomatic missions there.
"Now we are leading the action."