A guard sits on the rubble of the house of Brigadier Fouad al-Emad, an army commander loyal to the Houthis, after air strikes destroyed it in Sanaa, Yemen June 15, 2015. Warplanes from a Saudi-led coalition bombarded Yemen's Houthi-controlled capital Sanaa overnight as the country's warring factions prepared for talks expected to start in Geneva on Monday. REUTERS/Khaled Abdullah TPX IMAGES OF THE DAY

Houthi followers hold mock missiles and their rifles as they shout slogans during a demonstration against the United Nations in Sanaa July 5, 2015. REUTERS/Mohamed al-Sayaghi 

A Southern Popular Resistance fighter fires a weapon mounted on a truck during clashes with Houthi fighters in Yemen's southern city of Aden May 3, 2015. Between 40-50 Arab special forces soldiers arrived in Aden on Sunday and deployed alongside local fighters against the Houthi militia, a spokesman for the Southern Popular Resistance said. REUTERS/Stringer TPX IMAGES OF THE DAY

A girl cries next to her mother covering her face as they flee from an airstrike on an army weapons depot in Yemen's capital Sanaa May 11, 2015. REUTERS/Mohamed al-Sayaghi 

Houthi rebels transport part of a Saudi fighter jet found in Bani Harith district north of Yemen's capital Sanaa May 24, 2015. Local media said that the Houthi rebels brought down a Saudi F-16 fighter jet north of Sanaa early on Sunday. REUTERS/Khaled Abdullah TPX IMAGES OF THE DAY

Shi'ite Houthi rebels swim at the house of the business tycoon and Islah party leader Hameed al-Hamar after they took control of it in Sanaa September 24, 2014. The leader of a Shi'ite rebel group on Tuesday hailed the takeover by his fighters of much of the Yemeni capital after four days of fighting last week as a "successful revolution" for all citizens. REUTERS/Khaled Abdullah (YEMEN - Tags: POLITICS CIVIL UNREST) 

Houthi militants guard the house of Ali Haidar, a Houthi leader, destroyed by a Saudi-led air strike in Sanaa, Yemen, May 29, 2015. A guard was reportedly injured in the strike on the house, whose occupants had already evacuated prior to the strike, according to Houthis guarding the site and local media. REUTERS/Khaled Abdullah 

A Houthi follower holds up a rifle as he takes part in a demonstration against the United Nations in Sanaa July 5, 2015. REUTERS/Mohamed al-Sayaghi 

People flee as smoke billows after air strikes hit the house of Yemen's former President Ali Abdullah Saleh in Sanaa May 10, 2015. Saleh and his family are safe after airstrikes targeted his residence in the capital Sanaa early on Sunday, a news agency allied to the former Yemeni president said. REUTERS/Mohamed al-Sayaghi TPX IMAGES OF THE DAY

People walk past houses destroyed by a Saudi-led air strike in Sanaa July 3, 2015. REUTERS/Khaled Abdullah 

People look at the rubble of houses destroyed by a Saudi-led air strike in Sanaa June 21, 2015. REUTERS/Khaled Abdullah 

People display fragment of shells they collected from their house amid clashes between members of the anti-Houthi Popular Resistance Committees and Houthi fighters in Taiz, June 15, 2015. REUTERS/Stringer 

A Houthi militant stands amidst debris from a house of a Houthi leader Rafiq Rafiq, which was destroyed by a Saudi-led air strike, near Sanaa May 30, 2015. The Houthi militant is seen holding a picture of Rafiq Rafiq's son, who the Houthis say, was killed in the air-strike which destroyed the house. REUTERS/Mohamed al-Sayaghi 

A Houthi militant sits amidst debris from the Yemeni Football Association building, which was damaged in a Saudi-led air strike, in Sanaa May 31, 2015. REUTERS/Mohamed al-Sayaghi 

Girls wait for food rations outside a charity food assistance center in Sanaa July 1, 2015. REUTERS/Khaled Abdullah 

A guard stands on the collapsed roof of the house of General Ali al-Dhafif, a Yemeni army brigade commander, after it was hit by Saudi-led air strikes near Sanaa, Yemen, June 9, 2015. Four people, including two brothers of al-Dhafif, were killed in the strikes, a relative at the scene said. Al-Dhafif was not in or near the house when it was bombarded, the relative added. REUTERS/Khaled Abdullah TPX IMAGES OF THE DAY

Medics attend to a fighter of the Popular Resistance Committees at a hospital after he was injured during clashes with Houthi fighters in Taiz June 27, 2015. REUTERS/Stringer 

A woman sits near her father as he waits to be given a bed at a government hospital in Sanaa June 24, 2015. A country that was already by far the poorest and most unstable on the Arabian Peninsula is now, after three months of conflict, in the grip of a humanitarian disaster. REUTERS/Khaled Abdullah