Saturday night's suicide bombing is only the latest sign of the increasingly open struggle between the Saudi authorities and Islamic militants.
Dozens were killed in May's suicide bombings
Just six months ago the Saudi authorities liked to maintain there was no al-Qaeda activity whatsoever within the kingdom.
Then came two devastating suicide bombings in May killing 35 people.
That marked the beginning of a campaign by the Saudi authorities with a string of raids leading to the seizure of weapons, around 600 arrests and in some cases gun battles between police and militants.
As well as getting rid of Westerners from Saudi soil the militants want to get rid of the royal family themselves - seen by the militants as the corrupt puppets of the United States.
'Winning the battle'
So one unexpected consequence of the militant threat has been to push the Saudi royal family into a modest degree of political reform.
They are promising local elections next year as a means of shoring up their support among the majority of Saudis.
The royal family insist they are winning the battle against al-Qaeda and its allies saying that some militants are even being turned in by their own families.
The immediate concern for the 35,000 American and 30,000 expatriate workers is whether the Saudi authorities can guarantee their security.
The wider concern for Britain and the US is whether the pro-western Saudi royals can maintain the allegiance of most of their subjects or if support will drain away to the Jihadists who want to topple the royal family and wage war on the west.