Iran's relations with the fundamentalist Wahhabi Sunni sect that dominates Saudi Arabia is strained at the best of times. Iran was accused of planning a truck bomb attack that destroyed the US military base at Dharhran in 1996, and in 2003 the Revolutionary Guards were implicated in a series of similar bombings in Riyadh, the Saudi capital. Saudi also accuses the Revolutionary Guards of trying to foment unrest among its own Shia, who constitute around 5 per cent of its 19 million population. The majority live in the Eastern Province, which is also the location of Saudi's vast oil wealth. Last week, when Saudi anti-government demonstrators attempted to stage a "day of rage", most of the disturbances took place in the Shia towns, where the security forces fired tear gas and rubber bullets.