Supporters of opposition leader Leopoldo Lopez riot against police during a protest against Nicolas Maduro’s government in Caracas February 19, 2014. Tensions have risen in Venezuela since Lopez, a 42-year-old Harvard-educated economist, surrendered to troops on Tuesday after spearheading three weeks of often rowdy demonstrations against President Nicolas Maduro’s government. REUTERS/Carlos Garcia Rawlins (VENEZUELA – Tags: POLITICS CIVIL UNREST)