Houthi fighters take up position on a street during clashes near the Presidential Palace in Sanaa January 19, 2015. The Yemeni army and Houthi fighters clashed near the presidential palace in the capital Sanaa on Monday, a Reuters witness said, in the sharpest escalation of tensions since the Shi’ite Muslim movement took over the city in September. Gunfire and explosions were heard across the city and in close proximity to the palace of President Abd-Rabbu Mansour Hadi and the residence of the national security chief. REUTERS/Khaled Abdullah (YEMEN – Tags: POLITICS CONFLICT)