Amid deepening suspicions the Islamists are aided by al-Qaida's North African wing, which has been extending its operations southward of late, there are fears the bloodletting could plunge Africa's most populous state into a sectarian civil war.
Nigeria is a major oil producer that provides 8 percent of U.S. crude imports and there are signs that Washington is growing concerned about the swelling crisis there.
In October, U.S. Secretary of State Hillary Clinton vowed to take action against the main Nigerian Islamist group, Boko Haram, which until a few months ago was widely seen as a northeastern Nigerian sect primarily concerned with domestic issues.
But as the group, whose name translates as "Western education is a sin," has escalated its religious war from drive-by shootings and killing Christians to more sophisticated operations and suicide bombings, it has evolved into a serious threat to Nigeria's stability.
Formed in the 1990s, the group demanded Islamic Sharia law to be introduced into northern Nigeria, which is predominantly Muslim. But in recent years it has repeatedly clashed with Nigeria's Christians in the central region where the two religions collide.
Nigeria's population of 150 million is roughly split evenly between the two faiths.
But the country's oil wealth is in the Christian-dominated south and little has reached the long-neglected north, which has fanned regional resentment.
Boko Haram's growing expertise in terrorist attacks, in which hundreds of people have been killed, has deepened suspicions it has developed links with al-Qaida in the Islamic Maghreb, the jihadists' North African arm.
In November, it was disclosed that the U.S. Army has sent 100 Special Forces soldiers to Nigeria to provide counter-insurgency training for national troops engaged against Boko Haram, the country's largest military deployment since the 1967-70 Biafra war.
This opened up a new front in the U.S. administration's shadow war in Africa, where U.S. Special Forces and the Central Intelligence Agency are engaged in countering jihadist groups in the north and east, particularly Somalia.
On Nov. 30, the U.S. House of Representatives' subcommittee on counter-terrorism and intelligence identified Boko Haram as an "emerging threat" to the United States and its interests and called for greater interaction with Nigerian security forces.
Many counter-terrorism specialists viewed this as an exaggeration, inflating a threat that would help justify administration moves to become involved in combating insurgencies in African states, most of them dictatorial regimes, with Special Forces.
Through the U.S. military's Africa Command, established in 2007, the Americans are already training and equipping armies in Algeria, Burkina Faso, Chad, Mali, Mauritania, Morocco, Niger, Senegal and Tunisia.
Africa Command was ostensibly set up to aid U.S. allies on the continent build up their military capabilities.
But many in Africa believe its true function is ultimately to protect U.S. access to the emerging oil wealth in West and East Africa, that can be shipped directly to the United States across the Atlantic.
This would lessen U.S. dependence on Middle Eastern oil from the turbulent Persian Gulf, which is vulnerable to disruption, currently because of Iranian threats to block the strategic Strait of Hormuz, the only gateway in and out of the gulf.
On Oct. 14, U.S. President Barack Obama said he was sending another 100 U.S. troops to Uganda in East Africa, which recently found a major oil field in the Lake Albert basin containing an estimated 2.5 billion barrels.
Uganda is strategically positioned to be an export hub for the region's expanding oil wealth, as well as other mineral resources.
Obama said the deployment was to help Uganda strongman Yoweri Museveni crush a long-running insurgency by the cult-like Lord's Resistance Army led by a religious crackpot and international fugitive named Joseph Kony.
But the now much-diminished LRA has never posed a threat to the United States.
It may well be that Obama is rewarding Uganda for aiding the U.S.-backed Transitional Federal Government in neighboring Somalia fight the al-Shabaab Islamist group linked to al-Qaida.
Uganda could be a valuable jump-off point for U.S. forces to intervene in other potential trouble spots in East and Central Africa, where China is making major economic inroads, should that be deemed necessary.