Security checkpoints and roadblocks were erected inside and between Palestinian cities, subjecting all people and vehicles to security inspection for free passage. Israel defended those checkpoints as being necessary to stop militants and limit the ability to move weapons around. However some Palestinian, Israeli and International observers and organizations have criticized the checkpoints as excessive, humiliating, and a major cause of the humanitarian situation in the Occupied Territories. Transit could be delayed by several hours, depending on the security situation in Israel. Sniper towers were used extensively in the Gaza Strip before the Israeli pullout.