On the morning of Thursday, 17 January a car bomb exploded inside the grounds of the General Santander Police Cadet Academy in Bogota killing twenty-one (including the car driver) and injuring over seventy people. In a declaration sent on Monday, 21 January, the National Liberation Army (Spanish acronym, “ELN”), Colombia’s largest remaining guerrilla group, claimed responsibility. It declared the attack a legitimate act of war, because the attack was carried out against a police station. It also justified its actions by saying that the Colombian military carried out attacks against the ELN in December. The ELN had declared a unilateral ceasefire during December as a show of good faith in advancing a negotiation process that could lead to a permanent agreement.