Hundreds of troops from Chad and Niger launched a ground and aerial offensive against Boko Haram in northeastern Nigeria on Sunday, according to residents and military sources from Niger.

The sweeping offensive is taking place along the Niger-Nigeria border, sources said, effectively opening a new front in the fight against the Islamist terror group.

This comes a day after Boko Haram pledged allegiance to ISIS in an audio message purported to be from leader Abubakar Shekau.