A Tuareg-led rebel group said on Saturday it had launched an attack on the town of Anefis in northern Mali, where government forces and Russian paramilitary personnel are stationed, marking the latest escalation in the country’s security crisis.

The attack comes as Mali’s military-led government continues to face mounting security challenges following major rebel offensives in April that targeted Bamako’s airport, killed the country’s defense minister, and resulted in the capture of several military bases in northern Mali.

Mohamed El Maouloud Ramadan, spokesperson for the Azawad Liberation Front, told Reuters that the group’s fighters attacked Anefis in the Kidal region early Saturday.

Government and Russian forces had reinforced their presence in Anefis after the April offensive, during which the Azawad Liberation Front and an al-Qaeda affiliate seized control of the city of Kidal.