At least 200 people are feared to have been killed after Nigeria’s army struck a busy market as it pursued an Islamist militia group that has wreaked havoc across the country.

Though Nigerian President Bola Tinubu has recently claimed progress against the armed groups, much of Africa’s most populous country remains volatile, forcing millions to leave their homes.

US military assistance appears to have done little to help: Washington last week expanded its Nigeria travel warning and allowed embassy staff to leave the country, citing worsening safety concerns. Experts fear the security crisis could upend Nigeria’s economy, exacerbating a grave humanitarian crisis. “People have been cut off from all economic activity,” a UN official said.