Against the backdrop of a possible Palestinian bid for independence at the United Nations this September and thus far unsuccessful deliberations within the Quartet regarding terms of reference for restarting peace talks between Israel and the Palestinians, the issue of defensible borders merits renewed attention.Former foreign minister Yigal Allon was one of the clearest and most authoritative exponents of the case for Israel’s need for defensible borders. In an October 1976 article in Foreign Affairs, Allon noted that whereas Israel’s rivals seek to “isolate, strangle and erase Israel from the world’s map,” Israel’s strategic aims have been focused on its “imperative to survive.”Thus, even if peace agreements are reached, border and security arrangements must ensure Israel’s ability to defend itself in the event that such agreements are breached. As the recent upheavals in the Middle East have clearly demonstrated, this guiding principle has not lost its salience.Allon contended with a number of claims raised to counter Israel’s argument for defensible borders. Then, as now, technological advances such as missile technology were pointed to as obviating the need for strategic depth and topographical assets. Then, as now, international guarantees were pointed to as constituting a satisfactory substitute for physical control of defensible ground.Then, as now, such arguments did not coincide with anecdotal experience, drawn, as noted by Allon, from historical cases such as the German air ‘blitz’ against Great Britain, or the American air-strikes against North Vietnam, which demonstrated the limitations of air-launched attacks and continuing importance of having “boots on the ground.”Then, as now, such arguments failed to account for the resounding failure of international guarantees to ensure Israel’s security, as evidenced, for example, in UNEF’s withdrawal from Sinai in May 1967.Yet even beyond cases such as these, today we have the benefit of quantitative research which has shed a great deal of light on numerous international relations phenomena.Two research findings are of particular relevance in this regard: the strong correlation between extant territorial claims and violent international conflict and the positive association between conflict durability and insurgents’ access to an international boundary.The first indicates Israel has considerable grounds to expect security threats to persist, even subsequent to an agreement, as long as substantial Palestinian territorial claims to pre-1967 Israel persist. Thus, the fundamental source of potential conflict – the willingness – will in all likelihood continue.The second underscores the fact that access to an international border would provide Palestinian militants with the opportunity to continue – and expand – violent activities against Israel. As many scholars and observers of international relations have long understood, a conjunction of willingness and opportunity is an almost certain formula for violent international conflict.Thus, forcing Israel into indefensible borders, such as those of June 4, 1967, is unlikely to lead to a stable regional order.On the contrary, insofar as comparative, empirical research can serve as a guide, relinquishing an Israeli presence along some of the borders of a Palestinian state will severely diminish the chances of resolving the Israeli-Palestinian conflict and will probably exacerbate it. A cursory glance at developments in Gaza since Israel relinquished control of the Gaza-Sinai border in 2005 provides a rather stark confirmation of this basic observation.Territorial claims and conflict Over the past several decades, a very large, empirical literature has emerged which demonstrates the key role of territorial claims as a source of international conflict. Numerous studies, employing different research designs, varied spatial and temporal domains and independently conceived theoretical frameworks, have produced robust findings pointing in essentially the same direction, permitting a very decisive conclusion: territorial revisionism leads to violent international conflict.The particular value of this body of research is that the above conclusion has retained its validity, notwithstanding the numerous controls that have been imposed in different studies over the years.Irrespective of whether or not rivals sign treaties or commence their relations violently or peacefully, notwithstanding the variance in rivals’ cultural and historical background, or configuration of relative power, regardless of the rivals’ institutional structure (democratic or not) and level of economic development and taking into account the numerous other caveats that have been explored in the literature, the basic finding remains intact.While different factors have been shown to exert a mitigating effect on conflict, none appears capable of entirely vitiating the basic association between territorial revisionism and war.While it may appear trivial in some sense, the finding actually bears non-trivial policy implications. What it says, in effect, is that in instances where territorial claims cannot realistically be resolved, either through a negotiated or non-negotiated redistribution of land, violent conflict is likely to persist. This remains true, in particular, whether or not a formal treaty is signed between rivals. Indeed, empirical work on treaties has largely shown that while they are not mere “scraps of paper,” in the words of one of the prominent scholars in this field, they don’t generally appear to be capable of resolving disputed issues. At best, they may be able to manage them, primarily by affecting the incentives and degree of uncertainty facing potential rivals.The ramifications in the Israeli- Palestinian context should be clear, with regard to what can be realistically expected from a political settlement, at least at the present time. There can be no doubt that political forces such as Hamas and numerous fundamentalist affiliates would continue to harbor territorial claims regarding the pre-1967 territory of Israel, even were a peace treaty to be signed between Israel and the Palestinian Authority.The problem is further underscored by the positions of the Palestinian Authority.Its refusal to recognize Israel as a Jewish state, its objections to formulas such as “two states for two peoples” and its continuing commitment to the idea of having descendants of Palestinian refugees settle in Israel with the explicit goal of gaining demographic, and eventually political, control within it, reflect an ongoing nurturing of ultimately territorial demands for pre-1967 Israel. The extent to which Palestinian schools and popular culture venerate the idea of a “right of return,” and the consistency with which Palestinian leaders affirm support of it, reflect a firm commitment within a broad Palestinian constituency to these ethnically-based territorial claims.Might the Palestinian Authority disclaim these positions in the context of future negotiations? Perhaps, though it has revealed no indication of willingness to do so in eighteen years of talks. Recent revelations of internal, classified documents pertaining to Palestinian negotiating positions during the past decade, including on the question of refugees, have been extremely edifying in this regard, illustrating the very tangible, concrete nature of the Palestinian Authority’s ambitions with regard to the refugee question.Commissioning classified demographic studies that explored alternative scenarios for the influx of hundreds of thousands and potentially millions of Palestinians into Israel over a number of years, while contemplating the open-ended negotiation of additional migrations, presumably into perpetuity, these documents reveal a calculated, remarkably matter-of-fact vision for using the refugee issue as a means of acquiring demographic (and ultimately political) control of Israel.Yet, even if the Palestinian leadership were to renounce their call for “return,” would such a renunciation resonate with popular sentiments among Palestinians, sentiments that have been meticulously cultivated over decades? It seems unlikely.Would it reflect the views of millions of Palestinians kept in “refugee” status in neighboring states since 1948? It seems rather whimsical to suppose that it might.A sober analysis cannot but lead to the conclusion that very significant followings within Palestinian public opinion will continue to harbor territorial claims with respect to pre-1967 Israel, even subsequent to a possible Israeli-Palestinian agreement.The empirical literature on territorial claims – particularly those with an ethnic component – presents us, in turn, with the unfortunate conclusion that such claims can be expected to continue fueling violent conflict.Such conclusions are sometimes erroneously taken to imply a sense of determinism or inevitability as to the likely trajectory of the conflict. This is not, however, the case. Territorial claims to pre- 1967 Israel and tolerance for violence can be expected to persist in Palestinian society at least partly because they have been, and continue to be, deliberately cultivated by Palestinian elites, as has been extensively documented by organizations that monitor Palestinian society and media.Just as such motifs have been promoted over the years, so too can others, including those which may ultimately assist in fostering a culture of tolerance, territorial compromise and rejection of violence.The continuing salience of borders as a component of security As argued above, there is little reason to doubt that significant Palestinian territorial revisionism will persist, with its attendant potential for violence, whatever political arrangement emerges between Israel and the Palestinian leadership. A question may nevertheless be posed as to whether the location and topographical features of Israel’s borders will play a significant role in determining its security in such a context.Here too, as in the case of territorial claims, the theoretical and empirical literature is able to shed some light. It has long been argued by globalization theorists that geographical boundaries have been losing significance in the international arena. This trend is typically noted to be related to processes of transnational economic integration, alongside tremendous advances in communication and transportation technologies.The value of territory as a military asset has also been argued to be diminishing, inter alia, due to advances in missile and intelligence-gathering technologies. The significant decline in large-scale inter-state war in recent decades appears to corroborate this view.Yet, as noted by some scholars, borders do not generally seem to be losing in importance so much as changing their role.As Peter Andreas phrased it in his 2003 article in International Security: “In many cases, more intensive border law enforcement is accompanying the demilitarization and economic liberalization of borders.”The struggle against ‘clandestine transnational actors’ (CTAs), whether they come in the guise of organized crime or terrorist organizations, is becoming a growing concern for states concerned with safeguarding their borders against the infiltration of narcotics, weapons or illegal migrants. The post-9/11 focus on homeland security is symptomatic of this general trend.It is, therefore, not surprising that in recent empirical work on the subject of geography and rebel capability, covering civil conflict duration across the globe for much of the post-WWII period, it has been shown that “conflicts where rebels have access to an international border are twice as durable as other conflicts” (Halvard Buhaug, Scott Gates and Päivi Lujala [August 2009] “Geography, Rebel Capability, and the Duration of Civil Conflict.” Journal of Conflict Resolution 53(4): 544-569).The reasons are clear: such access serves as a life-line for the supply of weapons, funds, personnel, training, and, if need be, a safe haven, all of which can significantly enhance the relative capabilities of the insurgents and thus underpin protracted conflict.COUPLED WITH the inherent instability of the Middle East, vividly underscored in recent months, a realistic appraisal of Israel’s geopolitical situation behooves caution. In such circumstances, the importance of maintaining defensible borders is all the more plain, notwithstanding the general global trend towards a reduction in large-scale interstate war. Once again, empirical research is instructive in this regard: where territorial revisionism persists, so too does war.Some have argued that international guarantees and UN peacekeeping troops can serve as a substitute for direct border control by a concerned state. While findings have been reported revealing such measures to be capable of mitigating conflict, it has yet to be shown that they can decisively end it, where significant territorial claims persist.Tellingly, “identity” conflicts – those involving religious and ethnic aspects – prove significantly less susceptible to the irenic effects which treaties and international involvement may otherwise display. Also, multi-national troop deployments prove especially ineffective against groups determined to funnel illicit goods across a poorly secured boundary.This general observation gains very clear, specific expression in the Israeli-Arab arena.Hezbollah, with unhindered access to the Lebanese-Syrian border, has for years enjoyed a massive influx of missiles and other weaponry, supplied by Iran and Syria.Notwithstanding the efforts of an enhanced UNIFIL since 2006, Hezbollah has succeeded in increasing its arsenal to over 40,000 rockets, distributed throughout some 270 south Lebanese villages. The threat thereby posed to Israel, demonstrated as recently as 2006, when over 4,000 rockets were fired on densely populated areas in Israel, can scarcely be questioned.Hamas has similarly benefited from the fact that Israel no longer controls the border between Gaza and the Sinai Peninsula, transferring many thousands of rockets, mortars and other weaponry through tunnels burrowed under the border.Whereas the IDF presence on the Philadelphi Route in the 1967-2005 period could not prevent all weapons-smuggling efforts, the sheer magnitude of the weapons-smuggling operations since 2005, in terms of both quantity and quality of the armaments, belies any notion that control of the boundary has no military significance. The more than 9000 rockets and mortars that have struck Israeli territory since 2000 similarly illustrate the very tangible security threat thereby presented.Moreover, the pattern of rocket and mortar fire serves to illustrate the key role of border control. As documented in a March 2011 study by the Meir Amit Intelligence and Terrorism Center, in the five years subsequent to the Israeli withdrawal, the number of rockets and mortars that struck Israel increased by more than 150% to 6,535 compared with the 2,535 in the five year period prior to the withdrawal.Tellingly, whereas rockets, which are relatively sophisticated and effective, made up only 26% of fired projectiles in the earlier period, they accounted for 73% in the later period, reflecting the enhanced smuggling capacity of Hamas following the Israeli withdrawal.THUS, TO prevent the emergence of a heavily armed, hostile Palestinian state dominating Israel’s 15 kilometer wide heartland – precisely as has transpired pursuant to Israel’s withdrawal from Gaza and relinquishing of control over Gaza’s southern boundary – Israel will have to maintain a perimeter presence along the borders of a Palestinian state. This implies a continuing Israeli presence on the eastern boundary, that is, along the Jordan Valley.The viability of a Palestinian state Contrary to certain claims, maintaining an Israeli presence along the Jordan Valley is entirely compatible with the establishment of a contiguous, viable Palestinian state in Judea and Samaria.According to Palestinian statistics, based on a 2007 census, approximately 10,000 Palestinians reside in those parts of the Jordan Valley that were not already passed over to Palestinian civilian control under the Oslo Accords. This amounts to less than a half of a percent of the Palestinian population of Judea and Samaria, as documented by the Palestinian Central Bureau of Statistics. Moreover, the area lies exclusively to the east of the main Palestinian population centers, such that its omission would not interfere with the contiguity of a Palestinian state. Thus, excluding the Jordan Valley from the territory of a Palestinian state would have negligible demographic implications. By contrast, as argued above, the security implications would be weighty indeed, and probably critical with respect to the durability of a two-state arrangement.The stated Palestinian position is clearly incompatible with such a territorial division. Palestinian claims to the Jordan Valley form part of their claims to Judea and Samaria in its entirety, claims which compete with those of Israel to the same territory. Reflecting an appreciation for these conflicting claims, the terms of reference of the peace process, as expressed in the Oslo Accords as well as relevant United Nations resolutions, from Security Council Resolution 242 (1967) through to Security Council Resolution 1850 (2008), have consistently required that the borders, along with other disputed issues, be agreed upon between the parties. A priori rejection of the possibility that Israel will retain a presence in the Jordan Valley in a final status settlement is flatly inconsistent with the principle of mutual agreement and negotiations, which has underpinned every peace breakthrough thus far achieved between Israel and its neighbors.Thus, Palestinian opposition to a territorial division that would leave an Israeli presence in the Jordan Valley should not be confused with a claim as to its inherent infeasibility. Not only is such a division consistent with the implementation of a two-state solution, there are strong grounds, based on an analysis of the security reality which can be expected to emerge, suggesting the necessity of such a solution.THIS ANALYSIS does not imply that a stable, two-state solution to the Israeli- Palestinian conflict cannot be achieved. It simply underscores what such a solution would have to look like if it were to be genuinely stable. Contrary to views which regard the 1967 boundary as a sine-quanon for such a solution, empirical research suggests that a relinquishment by Israel of perimeter control of Judea and Samaria would be highly destabilizing.Such findings belie the idea that the mere presence of a signed agreement, or peacekeeping deployment, would obviate the need for Israel to retain tangible strategic assets as a component of its national security. Whereas this is a conclusion many observers of the conflict have intuitively understood for some time, today we have the benefit of quantitative empirical findings which serve to corroborate it.The writer serves as policy adviser to the minister of foreign affairs and lectures on game theory and territorial conflict at the Herzliya Interdisciplinary Center.