“In Bahrain, the majority of its population is Shia, but its government is Sunni and heavily linked to Saudi Arabia.
The Shiite population has not fared as well economically as Shia in other countries in the region, and tensions between the government and the public have long existed.
The toppling of the government of Bahrain by a Shiite movement would potentially embolden Shia in Saudi Arabia, who live primarily in the oil-rich northeast near Bahrain.
If the Saudis intervened in Bahrain, the Iranians would have grounds to justify their own intervention, covert or overt. Iran might also use any violent Bahraini government suppression of demonstrators to justify more open intervention. In the meantime, the United States, which has about 1,500 military personnel plus embassy staff on the ground in Bahrain, would face the choice of reinforcing or pulling its troops out.”
Unlike Libya, where the effects are primarily internal, the events in Bahrain clearly involve Saudi, Iranian and US interests.
Bahrain is also the point where the Iranians have their best chance, since it is both the most heavily Shiite nation and one where the Shiites have the most grievances.
But the Iranians have other targets, which might be defined as any area adjoining Saudi Arabia with a substantial Shiite population and with American bases.