The Camp David accords split the Sinai Peninsula into four zones, with differing levels of militarization allowed in each area. Egypt is permitted a mechanized infantry division with a total of 22,000 troops in Zone A, the westernmost area, while it is permitted four border security battalions to support the civilian police in Zone B. Only the Multinational Force and Observers, a U.N. peacekeeping force, and the Egyptian civilian police are permitted within Zone C. The Multinational Force and Observers is composed of three infantry battalions and several support units, including a coastal patrol unit and an aviation unit spread between two main bases and 30 smaller ones. In Zone D, Israel is permitted four infantry battalions. Israel has allowed exceptions to this agreement twice — once in 2005 when it allowed 750 border guards to come in after it withdrew settlements from the Gaza Strip and in 2011 when it allowed the deployment of about 3,500 troops with armored vehicles into Zone C. In mid-August, Egypt sent at least two attack helicopters, 80 vehicles, including light armored vehicles, and an unspecified number of troops and elite counterterrorism police to Zone C.