LAGOS, Nigeria — The leaders of two militant groups on Nigeria ‘s most wanted list have been arrested in an operation involving multiple agencies, the West African country’s national security adviser said Saturday.

The two leaders were allegedly the heads of Ansaru, an al-Qaida -linked group, and Mahmuda, a relatively new and lesser-known militant group. Mahmuda gained national prominence after a string of attacks earlier this year in the country’s north-central region.

Nigeria’s northern region is home to numerous armed groups.

Officials said the arrests came in an operation conducted between May and July and that they recovered valuable materials including digital evidence that is undergoing forensic analysis and could lead to more arrests.

The arrested leaders are Mahmud Muhammad Usman of Ansaru and Mahmud al-Nigeri of the Mahmuda group. Both men are also wanted internationally, according to Nuhu Ribadu, the security adviser.

“These two men have been on Nigeria’s most-wanted list for years. They jointly spearheaded multiple attacks on civilians, security forces and critical infrastructure,” Ribadu said at a news conference.

He said the arrested leaders are responsible for the Kuje prison attack in 2022 that led to the escape of dozens of jailed Boko Haram members and an attack on the Niger uranium facility in 2013, among others. Ribadu said they maintain “active links with terrorist groups across the Maghreb, particularly in Mali, Niger and Burkina Faso.”

Nigeria faces a complex, multidimensional security challenge with various armed groups operating across the country. On one side are religiously motivated groups, including 16-year-old Boko Haram and its splinter factions like Ansaru and the Islamic State West Africa Province. On the other are amorphous groups specializing in kidnapping for ransom and looting and commonly referred to as bandits. Sometimes, their activities overlap.

Despite military assaults on the groups, they have continued to expand their operations and carry out routine attacks. This year, Boko Haram has mounted a major resurgence.

The U.S. government on Wednesday approved the sale of $346 million in arms to bolster Nigeria’s fight against insurgency and criminal groups.

“The successful decapitation of the leadership of this dangerous franchise marks the most decisive blow against ANSARU since its inception. This strike has effectively dismantled its central command while paving the path for the complete annihilation of the group,” Ribadu said.

Oluwole Ojewale, a Dakar-based security analyst at the Institute of Security Studies, says the significant arrest will test the resilience of Ansaru and its capacity to spring surprises or mount major attacks in the immediate term.

“The impacts of this arrest on the terrorist groups depend on what the Nigerian state security does with the intelligence at their disposal,” he said.