TEHRAN, Oct. 19 (UPI) -- The weekend slaughter of several Revolutionary Guards generals in suicide bombings in the border province of Sistan-Baluchistan marked a sharp intensification of a slew of simmering insurgencies throughout Iran's restive frontier regions.
Tehran has accused the United States, Britain and Pakistan of fomenting the violence. All have denied any involvement, but over the years all have had reasons for stirring up trouble in the Islamic Republic, as have Saudi Arabia and Israel.
The violence has been growing since 2004 -- a year after the Americans invaded neighboring Iraq and found themselves trapped in an insurgency that was frequently fanned by the Iranians.
Amid a steady stream of bombings, assassinations and attacks on military personnel, Tehran has executed dozens of "traitors and criminals" and conducted mass arrests.
But the unrest has continued. The twin suicide bombings in Baluchistan Sunday, probably the work of the minority Sunni Jundallah, or Soldiers of God, group, was the deadliest strike yet by any of the insurgent forces and will likely trigger heavy retaliation by Tehran.
So far, the violence has been largely confined to the republic's peripheral regions -- oil-rich Sunni-dominated Khuzestan in the southwest; the opium-smuggling region of Baluchistan in the southeast, also Sunni; the Kurdish provinces in the west; and the Azeri region in the northwest that has produced many prominent Iranian leaders.
As the Iranians have sought to exploit the bloodbath in Iraq, the Americans and their regional Sunni allies have sought to destabilize the Tehran regime and keep it off balance in the confrontation over Iran's nuclear program.
It is unclear whether these covert efforts will continue as Washington and Tehran engage in public diplomacy to find a political accommodation in Iraq, but Sunday's slaughter indicates the stakes may be rising.
The Americans could decide that continued internal unrest would be a useful, and deniable, means of pressure on Tehran.
Most analysts say that despite Iran's ethnic diversity, a strong sense of nationalism is likely to hold sway over ethnic separatism, as it has in the past.
Saddam Hussein sought to exploit an ethnic uprising when he invaded Arab-dominated Khuzestan, the heart of Iran's energy industry, in 1980. But his rhetoric only united the country rather than divided it.
"While ethnic separation is not -- in the short-term at least -- a serious threat to Iran's cohesion and territorial integrity, it is widely feared that ethnic tensions could be exploited by Western powers, some of which are already active in intelligence-gathering and sabotage operations in some provinces," said analyst Mahan Abedin of the Jamestown Foundation, a Washington think tank that specializes in terrorism issues.
Only about half of Iran's 70 million people are ethnic Persians, although some 90 percent of the population adheres to the Shiite branch of Islam, which is the state religion.
Most of the estimated 15 million Azeris, Iran's second-largest minority, are Shiite, but most of the 5 million to 7 million Kurds and 4 million Baluchis are Sunni.
The 2 million Arabic-speaking Iranians in Khuzestan are overwhelmingly Shiite, but they are looked down upon by ethnic Farsi-speaking Iranians and are among the most disadvantaged groups.
These Shiites have become more restive and critical of Tehran's rule since their cousins in Iraq, Iran's western neighbor, were catapulted into power in Baghdad by the U.S.-led invasion of March 2003 that toppled Saddam's minority Sunni regime.
Tehran has proved itself adept at rallying Iranians against foreign threats and is pulling out all the stops in the current confrontation with the West.
But this resonates largely with the ethnic Persians rather than with the minorities who are more prone to outside influences.
Of all the regions gripped by anti-Tehran unrest, Khuzestan is the most strategic, and thus the most attractive target in any U.S. or allied effort to undercut Tehran's economic stability.
The province contains 66 percent of the country's recoverable oil and nearly 22 percent of its natural gas deposits.
According to 2006 statistics, it also holds 28 percent of Iran's refining capacity, 34 percent of its gas plants, 25 percent of its electricity generating plants and 26 percent of its petrochemical facilities.