In what could be a red flag that unrest is spreading to the Saudi kingdom, a human rights activist of indeterminate reliability reported March 1 that Saudi authorities had detained a Shiite cleric in the Eastern Province on Feb. 27. The cleric was arrested in the oil-rich and Shiite-heavy province after he delivered a Friday sermon calling for a constitutional monarchy. Saudi Arabia has been watching with extreme concern as a wave of unrest in the Persian Gulf region has hit Bahrain, where a Sunni monarchy presides over a Shiite majority; Oman, where the ruling sultanate is facing rare and widespread civil unrest; and Yemen, where the embattled president's political crisis is threatening to stir unrest among the Ismaili sect in Saudi Arabia's southwestern Jizan and Najran provinces.