Rebel fighters fire towards positions of regime forces in Ramussa on the southwestern edges of Syria's northern city of Aleppo on August 6, 2016. Syrian rebels said they have broken a three-week government siege of second city Aleppo, turning the tables on Russian-backed regime forces who are now on the defensive. (Photo by Fadi Al-Halabi/AFP Photo)

Gisele Marie, a Muslim woman and professional heavy metal musician, holds her Gibson Flying V electric guitar as walks down stairs at the end of a fund raising concert for the Syrian refugees in Brazil, in Rio de Janeiro November 8, 2015. Based in Sao Paulo, Marie, 42, is the granddaughter of German Catholics, and converted to Islam several months after her father passed away in 2009. Marie, who wears the burka, has been fronting her brothers' heavy metal band "Spectrus" since 2012. (Photo by Nacho Doce/Reuters)

A Syrian man rides his bicycle past a man selling grains during a halt in fighting on February 29, 2016 in Douma, in the Eastern Ghouta region, east of the capital Damascus. A UN-backed ceasefire deal took hold across parts of Syria, bringing relative calm to areas where the Islamic State group and Al-Qaeda's local affiliate are not present. (Photo by Sameer Al-Doumy/AFP Photo)

Rougine, a 19-year-old female Arab fighter among the Syrian Democratic Forces, made up of US-backed Kurdish and Arab fighters, stands in fatigues embracing another colleague near the village of al-Torshan, 20 km on the outskirts of Raqa on February 6, 2017. (Photo by Delil Souleiman/AFP Photo)

A man dressed as the “Star Wars” character Darth Vader sits on a bench in central Lviv, Ukraine, November 24, 2016. (Photo by Gleb Garanich/Reuters)

Three Chinese soldiers at the time of a civil war in China. (Photo by General Photographic Agency/Getty Images). 1922

Models of Cold War-era Allied (L) and Soviet Bloc weaponry face one another at the new Bundeswehr Military History Museum (Militaerhistorisches Museum der Bundeswehr, or MHM) on October 11, 2011 in Dresden, Germany. The museum, redesigned by star architect Daniel Libeskind, traces Germany military history from 1300 to the present, including during the Nazi period and the Cold War, and also examines the influence of the military on popular culture. (Photo by Sean Gallup/Getty Images)

Australian World War Two veterans place crosses and flags at graves before attending the French-British ceremony at the British War cemetery in Bayeux, June 6, 2014. REUTERS/Leon Neal/Pool