African leaders are stepping up their response to Boko Haram, with Chadian soldiers chasing the militants from a northern Nigerian town and the African Union calling for a 7,500-member regional force to tackle what it called “a serious threat” to the continent.

A communiqué adopted by the peace and security council of the African Union, which is meeting this week in Addis Ababa, Ethiopia, calls on Nigerian soldiers and their counterparts from four neighboring countries — Benin, Cameroon, Chad and Niger — to “prevent the expansion of Boko Haram,” search for those abducted by the group and conduct joint patrols at their borders. It does not specifically authorize the most sensitive step: cross-border operations.

According to a Chadian military spokesman, Nigerian news media reports and officials in Niger, Chadian forces took control on Thursday of Malam Fatori, a northern town that Boko Haram had held since October.

If confirmed, the recapturing of the town would indicate a breakthrough in regional military cooperation in the fight against the insurgents, which the Nigerian military has long viewed warily. A Nigerian Army spokesman said his troops had been involved in the operation, too, and another Nigerian official said his country “has never objected to cross-border operations in the fight against Boko Haram.”