ONE OF the thorniest problems in the way of a permanent Israeli- Palestinian peace deal is the question of an Israeli military presence in the West Bank portion of the Jordan Valley. At the heart of what is a highly complex affair, there are two key issues: The nature of the military threats Israel faces to the east, and whether adequate security arrangements can be found to meet them without impinging on Palestinian sovereignty.The threat Israel faced up to the early 1990s, which justified IDF deployment on the eastern slopes of the Samarian hills was the specter of several divisions of infantry and armor with air support sweeping towards Israel’s eastern border in a major ground offensive launched by a coalition of Arab states. This was seen as an existential threat because of the huge disparity in the size of the armies coupled with Israel’s relative lack of strategic depth. The military thinking then was that an IDF force deployed on the Samarian hills could block the Arab advance and afford greater strategic depth.Since then the strategic balance in the Middle East has changed beyond recognition. The threat of a massive land offensive is virtually non-existent. The disintegration of the Soviet Union removed the Arab “Eastern Front’s” main military backer; the collapse of Pan-Arab ideology reduced the chances of an Arab coalition; Israel signed peace treaties with two key Arab states, Egypt and Jordan, taking them out of the military equation; Iraq, a major component of the old “Eastern Front,” was heavily defeated in two Gulf Wars, severely reducing its military capacity; and Syria, another key player on the “Eastern Front,” is torn by civil war. As a result, even Prime Minister Benjamin Netanyahu is not demanding a significant Israeli presence in the West Bank to meet a threat that no longer exists.Shaul Arieli, a retired IDF colonel who headed the Peace Administration under Ehud Barak and was a prominent member of the 2003 Geneva Initiative, is a leading authority on the peace process with the Palestinians.For the foreseeable future, Israel will have to contend with two predominant military threats: “low intensity” guerrilla warfare or terror and the threat posed by strategic weapons, especially ballistic missiles and weapons of mass destruction. The two have a number of key factors in common. The main target in both cases is the civilian population; the mode of attack is primarily through the launching of rockets and guided missiles; and the aim is not victory on the battlefield but rather morale-sapping attrition and the reaping of perception- changing media dividends and political rewards.Clearly, the Jordan Valley is not relevant as a defensive buffer in either case.The range of the missiles and rockets covers all of Israeli territory without having to deploy even a single launcher west of the Jordan River. As for terrorists or guerrillas traversing Palestinian territory to strike at Israel, there are several existing and potential layers of defense: the stability of the Hashemite regime in Jordan and its success in preventing infiltration across its border into the Jordan Valley; the building of an obstacle similar to the border fence with Egypt, manned by well-trained forces; effective controls at border crossing points; the new Palestinian state’s capacity to suppress terror; and the deployment of Israeli forces to the west of the new border with Palestine.However, given the lack of any proven Palestinian capacity to prevent terror over time, I propose a phased agreement for the Jordan Valley, in which each stage lasts five years, and the transition from each stage to the next is subject to the Palestinian side meeting performance-based benchmarks. Phase 1: Israel retains a military presence along the Jordan River for the period that would anyway be needed for the evacuation of Jewish settlements, moving the existing security barrier in the West Bank to the new agreed border, and for the bulk of IDF forces to withdraw and redeploy outside the Palestinian state. During this period benchmarks for the forces replacing the IDF will be defined.Phase 2: Routine security activity is transferred from the IDF to an international force, which includes a select Palestinian force under its command. The IDF retains forces in small military installations in the Jordan Rift Valley for possible intervention in emergencies.Phase 3: Full responsibility for security is transferred to the Palestinian force. The international and IDF forces remain in small military installations for possible intervention in emergencies.Phase 4: The Israeli and international forces depart from the Palestinian state.This plan would be part of a larger framework of regional and bilateral security arrangements, an umbrella under which its chances of success would be greater. The wider framework would also provide Israel with agreed mechanisms for operating its forces, if and where necessary, vis-à-vis developments in the West Bank.The plan has advantages for the Palestinians too. Its terms guarantee the temporary nature of the Israeli presence. Moreover, the initial deployment of Israeli forces in the Jordan Valley would enable the Palestinian government to focus on law and order, suppressing terror in populated areas and building up its own forces for later deployment in the Jordan Valley.