Sassou also won the following presidential election in July 2009. According to the Congolese Observatory of Human Rights, a non-governmental organization, the election was marked by "very low" turnout and "fraud and irregularities". In March 2015, Sassou announced that he wanted to run for yet another term in office and a constitutional referendum in October resulted in a changed constitution that allowed him to run during the 2016 presidential election. He won the election believed by many to be fraudulent. After violent protests in the capital, Sassou attacked the Pool region, where the Ninja rebels of the civil war used to be based, in what was believed to be a distraction. This led to a revival of the Ninja rebels who launched attacks against the army in April 2016, leading 80,000 people to flee their homes. A ceasefire deal was signed in December 2017.