The top U.S. commander for Africa says the number of Islamic State militants in Libya has doubled in the last year or so to about 6,000.

Army Gen. David Rodriguez heads U.S. Africa Command. Rodriquez says local Libya militias have had some success in trying to stop the Islamic State from growing in Benghazi and are battling the group in Sabratha. But he says decisions to provide more military assistance to the Libyans will wait for a national government.

He says it will be a challenge for the Islamic State group to become as big a threat as it is in Iraq and Syria because of local Libyan fighters.