A television reporter tries to interview a non-responsive Ghiwa Jebran, 5, a Lebanese national, at her family's Riyadh residential compound Tuesday, Nov. 11, 2003 where a suicide bomb attack killed 17 people and wounded 122 Saturday night.(AP Photo/John Moore)

While Abdullah has been the de facto ruler since his half-brother Fahd's stroke in 1995, he now officially takes over as king and assumes ultimate responsibility for quelling al-Qaeda-linked extremism and managing his country’s oil policy.

While no major changes are expected in either of these areas, clearly Abdullah has his work cut out for him.

Over the past two years, the kingdom has suffered a violent campaign by Osama bin Laden's al-Qaeda network aimed at driving the royal family from power and replacing it with an Islamic caliphate.

In May 2003, suicide bombers killed 35 people in attacks at housing compounds for Westerners in Riyadh, prompting increased counter-terrorism co-operation between Saudi Arabia and the U.S.

Al-Qaeda is strongly opposed to Saudi Arabia’s alliance with the United States. In fact, 15 of the 19 al-Qaeda suicide bombers in the Sept. 1 attacks in the U.S. were Saudi citizens.

A Saudi man walks through the debris of the May 15, 2003 bombings in eastern Riyadh, Saudi Arabia, at the al-Hamra compound. (AP Photo/Hasan Jamali)

While Abdullah is widely expected to continue to co-operate with the U.S., he must balance his country’s close ties with Washington against increased anti-U.S. sentiments in Saudi Arabia.

In terms of oil, Abdullah has said he will adhere to Saudi Arabia’s long-time policy of keeping oil markets well-supplied and prices stable. But he is in his 80s and analysts worry about what will happen when Abdullah dies.

Saudi Arabia is after all the world’s largest producer of oil and its policies have enormous impact on our oil-dependent world economy.

"For the first time people are thinking about life after Abdullah. The succession there is not as clear," Rick Mueller, an analyst at Energy Security Analysis, told Reuters.

Oil prices briefly climbed to a high of $62.30 a barrel after the news of Fahd’s death, but the market later calmed down and traders seemed to understand that oil policy is unlikely to change in the near future.

Still, the new king’s designated heir to the throne, defence minister and Crown Prince Sultan, is also in his 80s. That means the question of who will take over once this generation of rulers is dead is of vital importance.

The unofficial third-in-line usually holds the position of second deputy prime minister, Prince Sultan’s former title. That position is currently vacant.

Analysts have voiced concern over the possibility that more conservative members of the royal family might move into positions of greater power after Abdullah’s death.