A Houthi militant recites prayers during a demonstration against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. The nothern-based Houthis, a Shi'ite Muslim group, took control of Sanaa last September. Arab countries intervened in the conflict in March to halt a Houthi advance into the south which caused the Saudi-backed government to flee to Riyadh from its refuge in the southern port of Aden. (Photo by Khaled Abdullah/Reuters)

Houthi followers demonstrate against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

A Houthi follower carries his weapon as he performs the traditional Baraa dance ahead of a demonstration against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

A Houthi militant secures an area where fellow Houthis demonstrated against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi followers demonstrate against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi followers hold up their rifles as they demonstrate against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi followers demonstrate against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

A Houthi follower carries his rifle and waves a dagger as he dances the traditional Baraa dance ahead of a demonstration against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

A Houthi follower carries his rifle as he dances with others the traditional Baraa dance ahead of a demonstration against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi followers demonstrate against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Armed boys join Houthi followers as they demonstrate against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi followers demonstrate against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

A Houthi follower carries his rifle as he performs with others the traditional Baraa dance ahead of a demonstration against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi followers perform the traditional Baraa dance ahead of a demonstration against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi followers perform the traditional Baraa dance ahead of a demonstration against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi followers demonstrate against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi followers hold up their rifles as they demonstrate against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi followers demonstrate against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi militants sit on the back of a patrol vehicle as they secure an area where fellow Houthis demonstrated against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Houthi militants sit in a vehicle as they secure an area where fellow Houthis demonstrated against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

Street vendors display flag posters of Yemen's Houthi leader Abdul Malik al-Houthi ahead of a demonstration by Houthi followers against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

A boy sells flag posters of Lebanon's Hezbollah leader Sayyed Hassan Nasrallah (L) and Yemen's Houthi leader Abdul Malik al-Houthi ahead of a demonstration by Houthi followers against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

A Houthi militant secures an area where fellow Houthis demonstrated against the Saudi-led air strikes in Yemen's capital Sanaa August 24, 2015. (Photo by Khaled Abdullah/Reuters)

A Shiite Houthi rebel holds his weapon as he attends a rally to protest Saudi-led airstrikes, in Sanaa, Yemen, Monday, August 24, 2015. The Saudi-led coalition fighting Shiite rebels in Yemen doubled its near-daily airstrikes in the central province of Marib and the adjacent border area of Jawf on Monday, paving the way for allies on the ground to push north toward Shiite rebel strongholds, military and security officials said. (Photo by Hani Mohammed/AP Photo)