State Department issues travel warning for portions of Nigeria
http://travel.state.gov/travel/cis_pa_tw/tw/tw_5985.html
The Department of State warns U.S. citizens of the risks of travel to Nigeria and recommends that U.S. citizens avoid all travel to Adamawa, Borno, and Yobe states because of the proclamation on May 14, 2013, by the government of the Federal Republic of Nigeria of States of Emergency in those three states. The ability of the Mission to provide assistance to U.S. citizens in those states remains severely limited. The Department also continues to recommend against all but essential travel to the following states due to the risk of kidnappings, robberies, and other armed attacks: Abia, Akwa Ibom, Bauchi, Bayelsa, Delta, Edo, Gombe, Imo, Jigawa, Kaduna, Kano, Katsina, Kebbi, Niger, Plateau, Rivers, Sokoto, and Zamfara. The Department also warns against travel to the Gulf of Guinea because of the threat of piracy. Based on safety and security risk assessments, the Embassy maintains restrictions for travel by U.S. officials to all northern Nigerian states (in addition to those listed above); officials must receive advance clearance by the U.S. Mission for any travel deemed as mission-essential. U.S. citizens should be aware that extremists could expand their operations beyond northern Nigeria to the country's middle and southern states. This Travel Warning replaces the Travel Warning for Nigeria dated December 21, 2012.
An extremist group based in northeast Nigeria known as Boko Haram has claimed responsibility for many attacks, mainly in northern Nigeria, which have killed or wounded thousands of people during the past three years. Multiple Suicide Vehicle-borne Improvised Explosive Devices (SVBIED) targeted churches, government installations, educational institutions, and entertainment venues in Adamawa, Bauchi, Borno, Gombe, Kaduna, Kano, Plateau, Taraba, and Yobe states.
Ansaru, an internationally-focused jihadist group considered an offshoot of Boko Haram, has operated in Nigeria since 2012. It has claimed responsibility for the kidnapping and execution of seven foreign nationals in Bauchi in early 2013, the kidnapping of a French national in Katsina in December 2012, and a November 2012 prison break at the headquarters of the Nigerian Special Anti-Robbery Squad in Abuja.
In 2013, extremists have also targeted both Nigerians and foreign nationals involved in polio eradication efforts in northern Nigeria. Several agencies that have partnered with the United States government in the field of public health development in northern Nigeria have curtailed their activities in response to these threats. Furthermore, U.S. citizen missionaries in northern Nigeria have received specific written threats to their safety and well-being, typically in the form of anonymously-distributed night letters (covertly-distributed anonymous threat letters intended to frighten intended victims).