Israel is building a fence or wall that, it hopes, will prevent terrorist infiltration into Israel from the West Bank Palestinian areas. Many Israelis endorse the fence as a way to stop terror attacks against Israel. Some Israelis oppose the fence because they believe it will become a permanent boundary that will stop Israel from annexing the West Bank. Other Israelis oppose the fence because they fear that it will become an obstacle to further peace negotiations. Most Palestinians oppose the fence because they believe it will define the boundaries of non-contiguous segments of a truncated Palestinian state. This CRS report includes known details on cost, dimensions, and location of Israel’s fences, and arguments supporting and opposing the West Bank fence now under construction. The report will not be updated.