After the 1995 Interim Agreements, the PNA took control of civil affairs in both designated Areas, A and B where ultimately all Palestinian population centers are located (except those within the municipal borders of East Jerusalem). Israeli Defense Forces became responsible for security in Area B. The Palestinian Central Bureau of Statistics took its first official census in 1997, and has not taken one since, however they have used provisional estimates to determine the current population. The most current estimate was in 2006. Shortly after, the Hamas took power in Gaza Strip, following the Battle of Gaza (2007) and became the de facto administration in the area.