Soldiers loyal to Yemen's government stand next to a damaged armoured vehicle at the frontline of fighting against Houthi militants in the central province of Marib, Yemen October 7, 2015. (Photo by Reuters/Stringer)





A tribal fighter loyal to Yemen's government rides a truck at the frontline of fighting against Houthi militants in the central province of Marib October 7, 2015. (Photo by Reuters/Stringer)





Soldiers and tribal fighters loyal to Yemen's government lie on the ground as they shoot at the frontline of fighting against Houthi militants in the central province of Marib October 7, 2015. (Photo by Reuters/Stringer)





A tribal fighter loyal to Yemen's government squats on the side on a slope at the frontline of fighting against Houthi militants in the central province of Marib October 7, 2015. (Photo by Reuters/Stringer)





A young tribal fighter loyal to Yemen's government rides in an armoured vehicle at the frontline of fighting against Houthi militants in the central province of Marib October 7, 2015. (Photo by Reuters/Stringer)





A tribal fighter loyal to Yemen's government removes a mine planted by Houthi militants at the frontline of an area controlled by the government, during their fight against the militants in the central province of Marib October 7, 2015. (Photo by Reuters/Stringer)





A truck passes near the fragments of a shell at the frontline of fighting against Houthi militants in the central province of Marib October 7, 2015. (Photo by Reuters/Stringer)





Tribal fighters loyal to Yemen's government ride a truck at the frontline of fighting against Houthi militants in the central province of Marib October 7, 2015. (Photo by Reuters/Stringer)





Fighters of the Popular Resistance Committees demonstrate their skills during a graduation ceremony of the affiliate special forces of the Popular Resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)





Fighters of the Popular Resistance Committees demonstrate their skills during a graduation ceremony of the affiliate special forces of the Popular Resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)





Fighters of the Popular Resistance Committees stand during a graduation ceremony of the affiliate special forces of the Popular Resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)





A fighter of the Popular Resistance Committees stands during a graduation ceremony of the affiliate special forces of the Popular Resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)





A fighter of the Popular Resistance Committees carries his weapon during a graduation ceremony of the affiliate special forces of the Popular Resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)





A fighter of the Popular Resistance Committees attends a graduation ceremony of the affiliate special forces of the Popular Resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)





Fighters of the Popular Resistance Committees ride in trucks after a graduation ceremony of the affiliate special forces of the Popular Resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)





Armed fighters of the Popular Resistance Committees escort their leader Hammoud Al-Mikhlafi (C) during a graduation ceremony of the affiliate special forces of the resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)





Tribal fighters loyal to Yemen's government ride a truck with their weapons at the frontline of fighting against Houthi militants in the central province of Marib October 8, 2015. (Photo by Reuters/Stringer)





Soldiers loyal to Yemen's government stand next to a tank on the side of the road at the frontline of fighting against Houthi militants in the central province of Marib October 8, 2015. (Photo by Reuters/Stringer)





Tribal fighters loyal to Yemen's government ride a truck as they pass a barrel with a flag of Yemen sticking out from it at a check point on the frontline of fighting against Houthi militants in the central province of Marib October 8, 2015. (Photo by Reuters/Stringer)





Soldiers and tribal fighters loyal to Yemen's government wallk at the frontline of fighting against Houthi militants in the central province of Marib October 8, 2015. (Photo by Reuters/Stringer)





Soldiers loyal to Yemen's government ride a truck at the frontline of fighting against Houthi militants in the central province of Marib October 8, 2015. (Photo by Reuters/Stringer)





Tribal fighters loyal to Yemen's government ride a motorcycle as they pass by a destroyed tank on the side of the road at the frontline of fighting against Houthi militants in the central province of Marib October 8, 2015. (Photo by Reuters/Stringer)





Soldiers loyal to Yemen's government ride a truck with their weapons at the frontline of fighting against Houthi militants in the central province of Marib October 8, 2015. (Photo by Reuters/Stringer)





Fighters of the Popular Resistance Committees stand during a graduation ceremony of the affiliate special forces of the Popular Resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)