Nigeria and three other states have pledged to speed up the creation of a 2,800-strong regional force to tackle militant Islamist group Boko Haram.
Defence ministers of Nigeria, Cameroon, Chad and Niger said they would each contribute 700 troops to the force.
Niger's Defence Minister Karidio Mahamadou said they were determined to "eradicate this curse".
Boko Haram's insurgency is focused on Nigeria, but it has carried out some cross-border raids.
It was suspected of blowing up the Ngala bridge, which lies on a key transport link between north-eastern Nigeria and Cameroon, on Wednesday.
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