U.S. intelligence estimates now put the number of ISIS fighters in Libya between 4,000 to 6,000, double the number in the war-ravaged country last year, according to the top U.S. military commander in Africa.

Gen. David Rodriguez, commander of U.S. Africa Command, said the intelligence community estimates the number of ISIS fighters in Libya at “around 4 to 6,000.” He added that the number has “probably about doubled in the last 12 to 18 months, based on what their assessments were last year.”

Wracked by violence since the fall of Moammar Gadhafi in 2011, Libya has become a haven for militant groups.

From 2014, the country was divided between two rival governments, one in the capitol of Tripoli and another in the east. A December deal created a Government of National Accord that the United Nations and Western governments hope can unite the country’s armed factions against ISIS and set Libya on a more stable course.