Trouble in Yemen

Houthi fighters ride a truck while patrolling a street in Sanaa January 21, 2015. REUTERS/Khaled Abdullah

A military vehicle belonging to the presidential guards, which was seized by Houthi fighters during clashes, imore

A Houthi fighter stands atop an armored vehicle, which was seized from the army during recent clashes, outsidemore

A Houthi fighter screens members of the Yemeni presidential guards who are wearing civilian clothes, as they lmore

Houthi fighters ride a military truck outside the Presidential Palace in Sanaa January 21, 2015. REUTERS/Khalmore

A Houthi fighter mans a machine gun atop a military vehicle, seized from the presidential guards during clashemore

Houthi fighters sit at a post taken from presidential guards after clashes near the Presidential Palace in Sanmore

A Houthi fighter mans a checkpoint on a road leading to the U.S embassy in Sanaa January 21, 2015. REUTERS/Mohmore

Houthi fighters stand near a damaged guard post at a Presidential Guards barracks they took over on a mountainmore

A Houthi fighter walks past damaged shops outside a Presidential Guards barracks on a mountain overlooking Premore

Houthi fighters sit on top of a military truck which was seized from the army during recent clashes, outside tmore

Houthi fighters walk outside the Presidential Palace in Sanaa January 21, 2015. REUTERS/Khaled Abdullah

Houthi fighters ride in a truck on a street leading to the Republican Palace in Sanaa, January 20, 2015. REUTEmore

A Houthi fighter checks a car at a checkpoint on a road leading to the Presidential Palace in Sanaa January 20more

People walk past a van burnt down during clashes between Houthi fighters and Presidential Guard troops near thmore

Houthi fighters take up position on a street during clashes near the Presidential Palace in Sanaa January 19, more

Presidential troops block a road leading to the presidential palace in Sanaa January 20, 2015. REUTERS/Khaled more

A vehicle from the Presidential Protection Forces is seen positioned outside the house of President Hadi durinmore

A man carries his belongings as he flees from an area near the near the Presidential Palace while Houthi fightmore

A vehicle from the Presidential Protection Forces is positioned on a street during clashes near the Presidentimore

A tank from the presidential guard is seen at a barrack taken over by Houthi fighters, on a mountain overlookimore

Houthi fighters operate a checkpoint on a street leading to the Presidential Palace during clashes in Sanaa Jamore

A Houthi fighter wears a traditional dagger with a picture of a slain comrade as he poses for a photo outside more

A member of the presidential guards stands on an armoured personnel carrier blocking a road leading to the premore

A military vehicle belonging to Houthi fighters is positioned on a street leading to the Presidential Palace dmore

A Houthi fighter poses for a photo outside a presidential guards barrack on a mountain overlooking the presidemore