Ten days ago, in Damascus, I sat down with a Syrian official I've known for years and asked the question on everyone's mind. What's with the jihadists crossing Syria's border into Iraq? There is no way anyone can control a long border like that, he said, sounding the official line. Then he dropped a bombshell. Of 1,200 suspected suicide bombers arrested by Syrian authorities since the beginning of the war in 2003, 85 percent have been Saudis.

Eighty-five percent? This can't be good. Saudi Arabia sits on 25 percent of the world's proven oil reserves. It is the only producer with enough spare capacity to stabilize oil markets during crises. So what if these jihadists crossing from Syria into Iraq decide, sooner or later, to take their war back home, perhaps by attacking the kingdom's oil infrastructure in the same way the Iraqi resistance is doing in Iraq? That's a scenario that keeps Washington awake at night.

Fine, last week's royal succession went smoothly. Fahd died, his half brother Abdullah ascended the throne and Sultan, the Defense minister and Fahd's full brother, became crown prince. Saudis all across the kingdom flocked to swear allegiance to their new king. Oil markets barely moved, thanks largely to presumptions about Abdullah's good intentions. He has proved himself a pragmatic reformer over the past decade, managing the kingdom in the incapacitated Fahd's name, moving against royals' corruption and setting up this year's municipal elections--a genuine democratic step. Among commoners at home, he is the most popular prince. Abroad, he's liked because he does not hesitate to goose Saudi production when needed.

But there's a hitch. Like Abdullah himself, at 81, the senior princes are getting old. Who, then, comes next? Abdullah's accession went smoothly partly because he agreed to keep Fahd's full brothers, the so-called Sudeiris, in line to succeed him. Foremost among the contenders is Abd al-Majid, the governor of Mecca and a half brother of Fahd and Abdullah, now in his 50s. Sultan would like to groom his own son Khalid, the assistant minister of Defense and a commander during the first gulf war, for inclusion in the line of succession. But Khalid carries a lot of baggage--among them charges of gross corruption--and is not popular with other senior princes. Saud Al-Faisal, the foreign minister, and his brother Turki Al-Faisal, the former intelligence chief and ambassador designate to Washington, have also been considered as potential compromise candidates. Neither is thought to be acceptable to the family, however, while Prince Bandar bin Sultan, another son of Sultan and until recently the U.S. ambassador to Washington, is tainted by his too-close American connections to be acceptable to the conservative clerical establishment.

From a Western perspective, all this suggests a reassuring period of calm status quo, with uncertainties postponed until the next succession. Or does it? In fact, the Abdullah of tomorrow could well be very different from the Abdullah of the past decade. For starters, he is furious about the Iraq war. He opposed it from the outset, believing Saddam should have been left in place. And being a Sunni himself, he certainly didn't want to see the Sunni minority driven from power. Moreover, Abdullah's mother and wife are from the Shummar tribe, a key group in the Iraqi Sunni resistance. In other words, U.S. troops are killing his relatives.

Increasingly, the new king's anger is mixed with alarm. During the last few months, the Iraqi resistance has been firing at Saudi and Kuwaiti border posts. So far it's nothing serious--but it could be a harbinger of Iraq's chaos spilling into the kingdom. Iran is no less a problem. Two months ago, in Qum, I spoke with Grand Ayatollah Saanei about the phenomenon of suicide bombings. I expected the usual diatribe against the United States but instead his real anger was directed at the "Wahhabi" suicide bombers, almost all of them Saudis, killing Iraqi Shia. "They are wolves without pity," he said. "Sooner rather than later, Iran will have to put them down."

Put them down? The ayatollah offered no specifics, but the implications, as Abdullah would interpret them, are profoundly unsettling. Saudi Arabia has a large Shia minority that sits astride its main oilfields. What would prevent the Iranians from stirring them up? Or redirecting those Saudi jihadists crossing over from Syria?

All this will force Abdullah to face the question of Saudi-backed terrorism. Until today, the Saudis either would not or cannot identify the recruiters of the 15 Saudis who ended up on the planes on 9/11--or identify who in Saudi Arabia provided the cash for the attacks. Nor can Abdullah be sure that this grass-roots terrorism will not turn against Al Saud. With problems like these, he's unlikely to begin addressing more basic problems, such as structural unemployment (estimated at 30 percent), runaway population growth and an ultimately fatal dependence on oil.

Saudi royals may have put a good face on the succession. But let's not delude ourselves. When it comes to jitters over Saudi Arabia, we're talking about a lot more than just a spike in oil prices.