Back when the Libyan government was still an actual government, and still in Tripoli, former General Khalifa Hifter announced his intentions to take the country over militarily. The government now holds much less territory, and just in the east, but Gen. Hifter is still a thorn in their side.
Some of it is their own fault. After losing the capital, the Thinni government gave Hifter an official position of leadership in the Libyan Army, hoping he would retake the country for them. He quickly merged his own self-proclaimed army with what was left of the actual army, and became all the stronger.
He wasn’t able to retake the country, but he has convinced supporters in many eastern cities, including Benghazi, to take to the street to demand that the government be replaced by a military council, with him in charge.
That the rallies make twin demands of military rule and the ban of the Muslim Brotherhood makes it pretty obvious that Egypt has its hands deep in this affair, with the Egyptian junta keen to export the system of military rule to its neighbor, and keen to ban the Muslim Brotherhood, which was the elected government in Egypt before the 2013 coup, anywhere and everywhere, as a “terrorist organization.”
Egypt has repeatedly expressed support for Gen. Hifter, and has launched air strikes in support of him during his previous attempts to take over the country.