The arrest of 16 Saudi nationals, along with two foreigners, on charges of spying for an unnamed foreign government are the latest example of how relations between the kingdom’s Sunni rulers and the Shia-dominated Eastern Province have deteriorated.

Riyadh has long blamed Iran for stirring up trouble among the Shia in the oil-rich Eastern Province, and in neighbouring Bahrain. This has masked increasingly vocal calls for reform.

King Abdullah bin Abdulaziz al-Saud’s strategy of slow and steady reform has led to significant economic diversification and development. Large sections of Saudi society have missed out on the benefits of this. Recent largesse should be felt more widely, particularly the introduction of unemployment benefits, and also plans to spend billions of dollars on housing and healthcare projects.

Political reform has been slower in moving forward. A landmark move to appoint women to a third of the seats in the consultative Shura Council is among the most significant political reform of recent years. But this too has only limited impact on the wider population.

Conservatives in Saudi Arabia fear that the Arab Uprisings are emboldening local activists to demand faster reform. The recent sentencing of two Shia activists to 10 years in prison is viewed as a warning that the regime’s critics need to stop stoking unrest.

That tactic is unlikely to work. Riyadh will have to engage more actively with the demands coming out of the Eastern Province, even if it does not meet them all, if it wants to restore stability to the area.