Police have gone on a heightened state of alert for the seven-day Pessah holiday, forming three rings of security extending from the border with the West Bank to city centers. Terrorist organizations "have an increased motivation" to carry out an attack in the wake of Operation Cast Lead, police believe. A police statement released on Sunday detailing preparations cited a recent surge in attacks, including Saturday's gun attack on a Border Police base near Beersheba, a fatal ax attack at the Bat Ayin settlement, and an attempted car bombing at a Haifa mall. An increased police presence will be felt across the inner cities, and in markets, shopping centers and other population centers. Mobile checkpoints will spring up at the entrances and exits of cities. Police will also increase forces in and around Jerusalem. Attempts by Palestinians to illegally enter Israel will meet with increased enforcement in the coming days, as terrorists use routes used by illegal workers to infiltrate the country. Police will seek to crackdown on anyone caught transporting, employing or providing room and board to Palestinians who crossed into the country illegally. At international border crossings, police have been instructed to make more stringent checks. On Pessah eve (Wednesday), police will switch to Alert Level C, Shield 3, which see the three rings of security beefed up further. Patrols around synagogues will be increased. Police officers have themselves become a target in the last number of weeks, with two Traffic policemen shot dead in a terrorist ambush in the West Bank, and a Border Police base coming under fire on Saturday. Israel Police spokesman Micky Rosenfeld said daily assessments were being held to coordinate responses to possible attacks, but that officers on the ground were not being told to follow new procedures.