An ambush by a “terrorist group” killed 21 Nigerien soldiers near the country’s border with Burkina Faso on Tuesday, Niger’s ruling military junta said in a statement read on national television.

The statement Tuesday evening did not specify which group was behind the attack. Niger is struggling with a deadly security crisis involving several armed groups.

Last week, the rebel Patriotic Liberation Front attacked a China-backed pipeline and threatened more attacks if the $400 million deal with China isn’t cancelled.

The group, led by Salah Mahmoud, a former rebel leader, took up arms after the junta staged a coup last year ousting a democratically elected government.

Niger and neighbouring Mali and Burkina Faso are also battling movements linked to al-Qaida and the Islamic State extremist group in a decade-long conflict in the Sahel region that is worsening.

The violence killed thousands of people last year, and more than two million people have been displaced, according to the United Nations

Mali and Burkina Faso are also led by juntas and have experienced two coups each since 2020.

Both juntas have expelled French forces and turned to Russian mercenaries as they struggle to quell the Islamist groups.