ABUJA — Nigeria's security forces went on high alert over planned attacks by Islamist militants on public infrastructure in the capital city of Abuja and in Niger state, according to an internal memo dated April 13. The planned targets include the international airport and a prison facility in Abuja and a military detention center in neighboring Niger state, the memo said.

The memo said the planned attacks would be carried out by sleeper cells of the Islamic State West Africa Province, known as ISWAP, and Boko Haram. "Their intention is to release detained terrorists and inflict significant damage on critical aviation infrastructure," the memo reads.

The memo drew a parallel to an attack in Niger Republic in January, in which Islamist militants targeted an air force base in Niamey. "An analysis of the report reveals a concerning correlation between the potential targeting of the Nnamdi Azikiwe Airport Abuja and recent large-scale attacks on aviation facilities in Niger Republic, notably in Niamey and Tahoua. This suggests a possible intent by terrorists to replicate the attack patterns within Nigeria," the memo says.

In 2022, an attack on the Abuja prison facility led to the escape of 879 inmates, including 64 members of ISWAP. That incident involved the same facility now identified as a planned target in the April 13 memo.

Nigeria, Africa's most populous country, faces an insurgency in its northern region that has lasted more than a decade, with armed groups kidnapping people for ransom. Among the most prominent Islamic militant groups in the country are Boko Haram and its breakaway faction ISWAP. The Lakurawa group, linked to the Islamic State, operates in communities in northwestern Nigeria near the border with Niger Republic.

Last week, the United States authorized its non-emergency government employees and their families to leave the U.S. embassy in Abuja, citing an increase in terrorist attacks, kidnappings, and violent crimes in Nigeria, particularly in the north. The embassy has been closed. A Nigerian government official said the U.S. decision to close the embassy was a routine precaution guided by internal protocols and did not reflect the overall security situation of the country.