Libyan forces allied with the U.N.-backed government fire weapons during a battle with IS fighters in Sirte, Libya, July 21, 2016. (Photo by Goran Tomasevic/Reuters)

A fighter of Libyan forces allied with the U.N.-backed government runs for cover during a battle with Islamic State fighters in Sirte, Libya, July 31, 2016. (Photo by Goran Tomasevic/Reuters)

A Libyan rebel fires on a government jet as a natural gas facility burns on the frontline on March 9, 2011 near Ras Lanuf, Libya. The rebels pushed back government troops loyal to Libyan leader Muammar Gaddafi towards Ben Jawat.

A member of Libyan forces allied with the U.N.-backed government fires a weapon on a pickup truck during a battle with Islamic State militants in Giza Bahreya, in Sirte, Libya October 27, 2016. (Photo by Hani Amara/Reuters)

A fighter of Libyan forces allied with the U.N.-backed government fires a shell with Soviet made T-55 tank at Islamic State fighters in Sirte, Libya, August 2, 2016. (Photo by Goran Tomasevic/Reuters)