ABUJA, Nigeria — Islamic militants attacked a military base in northeast Nigeria killing five soldiers, the Nigerian army said Friday.

The base located in Mandaragirau in the Biu area of Borno state was attacked by “terrorists” early Friday, army spokesman Haruna Sani said in a statement.

The army did not specify what group was responsible, but it has linked similar attacks to the militant group Boko Haram or its splinter faction, the Islamic State West Africa Province, or ISWAP. IS is known for attacking military formations in the country’s northeast.

Sani said the troops repelled the attack and inflicted casualties on the assailants, who launched the assault under severe weather conditions.

“The counterassault underscores the resilience of the troops at (forward operating base) Mandaragirau, and reflects the courage and determination of our troops across the theatre,” he said.

Nigeria faces a complex security crisis, especially in the north, where an insurgency more than a decade old is located and armed groups carry out kidnappings for ransom.

Last month, the West African country said its joint operation with the United States had killed 175 ISWAP fighters, including top commanders of the group.

The insurgency in Nigeria’s northeast has killed thousands of people and displaced millions, according to the United Nations.