A core element of President Barack Obama’s much-anticipated speech in Cairo was an old idea: a two-state solution for the Israeli-Palestinian conflict. As expected, he argued strongly on its behalf, saying it “is in Israel’s interest, Palestine’s interest, America’s interest, and the world’s interest.” He pledged to “personally pursue this outcome with all the patience and dedication that the task requires.”

Obama’s effort is the latest in a long line of such efforts, none of which have been successful. In 1947 the United Nations Special Commission on Palestine (UNSCOP) endorsed the idea of two states for two peoples as a way of resolving the Arab-Zionist conflict over the Holy Land. The Commission members were not the first officials to suggest splitting the contested territory, but when the United Nations General Assembly (UNGA) voted on November 29, 1947 to approve UNSCOP’s majority report, they were the first to win the backing of the international community. The Zionist movement accepted partition, and on May 14, 1948, Zionist leaders established the State of Israel.

Most Palestinian leaders rejected the idea of voluntarily ceding more than half of Palestine to the Zionists, as the UNGA resolution proposed. They wanted a self-determination process that took account of their history of habitation and numerical superiority. During the 1948 War that followed, Egypt, Israel, and Jordan all seized pieces of what the UNSCOP members intended to be a new Arab state. Israel emerged about 40 percent larger than planned; Egypt had control of the Gaza Strip; and Jordan soon annexed the West Bank, including East Jerusalem.

In the wake of the 1967 war, when Israel captured both the Gaza Strip and the West Bank, the idea of a two-state solution became increasingly central to diplomatic efforts. Many have described it in the way Churchill described democracy: the worst form of government, except for all the alternatives. The United States, United Nations, Arab League, Russia, and the European Union have all supported it. Many hoped the Oslo process (1993-2001) would lead to a two-state solution; Bill Clinton’s December 2000 parameters provided a blueprint for two states; and George W. Bush’s 2007 Annapolis process aimed at resolving the so-called final-status issues of borders, Jerusalem, refugees, and settlements, thereby paving the way to a two-state solution.

The Arab League plan of 2002, reaffirmed in 2007, was equally supportive of a two-state solution, as it called on Israel to accept “the establishment of a sovereign independent Palestinian state on the Palestinian territories occupied since June 4, 1967 in the West Bank and Gaza Strip, with East Jerusalem as its capital.” The Arab countries have pledged to “establish normal relations with Israel in the context of this comprehensive peace.” Security Council Resolutions 1850 (2008) and 1860 (2009) sought, in the language of 1860, “a comprehensive peace based on the vision of a region where two democratic States, Israel and Palestine, live side by side in peace with secure and recognized borders.”

Obama, therefore, is preparing to enter familiar territory.

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Despite this overwhelming official support, the two-state solution faces several fundamental challenges, and many thoughtful observers wonder whether its time has passed.

Israeli settlements in the West Bank are deeply entrenched and growing rapidly. As early as the mid-1980s, some Israelis argued that it was too late for a complete Israeli withdrawal from the West Bank. But the first intifada (1987-1993), Oslo process (1993-2001), and second intifada (beginning in 2000) convinced many Israelis that the idea of Greater Israel–pre-1967 Israel plus, ultimately, much of the West Bank–was not a viable path. The Gaza disengagement in 2005, in which Israel removed about 9,000 settlers from the Gaza Strip, seemed to confirm that trend.

Yet in 2009 Israel has close to half a million settlers in East Jerusalem and the rest of the West Bank. The Israeli NGO Peace Now reported that 2008 Israeli construction in settlements outpaced that of 2007 and that government approval is granted or pending for 73,300 new housing units in the West Bank. Just before the 2009 Israeli election, Israeli Minister of Defense Ehud Barak, head of the Labor Party, approved a new settlement (though it was portrayed as a new neighborhood of an existing settlement). The move may have been for electoral gain, but it is telling that a Labor Party leader felt compelled to burnish his settlement credentials.

In addition to splintering Palestinian society territorially, the settlement project and occupation also create economic, political, and social obstacles to the integration of a Palestinian political community. For example, Israel makes it difficult for Palestinians in East Jerusalem to legally expand their homes, and when, as a result, they move to nearby towns, they face difficulty returning. Each year Israel strips a few hundred or more Palestinians of their right to visit East Jerusalem by arguing they have left and do not spend enough time in the city to be granted access.

In January 2009 Daniela Weiss, a settler leader, announced triumphantly in a 60 Minutes story: “I think that settlements prevent the establishment of a Palestinian state in the land of Israel. This is the goal. And this is the reality.” Meron Benvenisti, a former deputy mayor of Jerusalem appearing in the same story, was pessimistic about the possibility of two states because “you cannot unscramble that egg.”

In 2000 and again in 2008, Israeli and Palestinian negotiators sought to address the settlement challenge through creative map-making. They agreed that in East Jerusalem, Israel could annex Jewish neighborhoods, and that would take care of just over half the settlers. In addition, Israel sought to annex large settlement blocs in the West Bank such as the Etzion bloc, south of Jerusalem, and Ma’ale Adumim, a large suburb east of Jerusalem. Israel hoped that it would annex as many as 80 percent of the settlers. At the same time, the two sides agreed to land swaps in which Israel would compensate the Palestinians for this annexed territory with some land taken from pre-1967 Israel that would become part of Palestine.

Israel might be more open to the right of return if its implementation precludedactual return to Israel.

Even if such creative bargaining worked for settlements and territory, the two sides might still be stymied by the holy sites in Jerusalem and the Palestinian refugees, issues less amenable to negotiation. In the Old City of Jerusalem, the Noble Sanctuary (Haram al Sharif), holy to Muslims, sits on top of the Temple Mount (Har Habayit), holy to Jews. Two mosques, the Dome of the Rock and al Aqsa, sit cheek to jowl with the Western Wall, the standing remains of the ancient Jewish Temple and the holiest site in Judaism today. President Clinton, in his 2000 parameters, and Michael D. Bell and Daniel C. Kurtzer, in a spring 2009 Foreign Affairs article, proposed creative ideas for splitting or sharing this area, but the parties in conflict have not agreed upon any particular formulation.

Since their expulsion and flight of 1948, Palestinian refugees have claimed, with considerable international support, a right of return to their homes in pre-1967 Israel, even though those homes were demolished by Israel or taken over by Jewish immigrants. Israel will not compromise on the right of return because it could mean millions of Palestinians coming to Israel and negating its identity as the Jewish state. Israel, however, might be more open to the right if its implementation precluded actualreturn to Israel. Some Israeli negotiators over the last decade have accepted a symbolic return of tens of thousands of Palestinians to Israel itself, but these proposals do not have widespread support among Israeli Jews.

Strong Israeli and Palestinian leaders, with the help of excellent mediation, might be able to overcome even these impediments to a negotiated agreement. Negotiations are, after all, about trade-offs. But political fragmentation on both sides thwarts the development of the necessary political will. Since 1992 Israel has had six prime ministers. Yitzhak Rabin was assassinated, while Shimon Peres (1995-96), Benjamin Netanyahu (1996-99), and Ehud Barak (1999-2001) were all defeated at the polls in early elections. Ariel Sharon has been comatose since 2006. Former Prime Minister Ehud Olmert stepped down in March 2009 due to a personal and political scandal. The biggest winners in the Israeli election of February 2009, Kadima and Likud, each mustered just under one-quarter of the Knesset–not a recipe for coalition stability as Netanyahu returned to the prime minister’s office.

Palestinian political fragmentation is even more pronounced. In June 2007 Hamas seized full control of the Gaza Strip. Since then, the Palestinians have had two governments, one led by Hamas’s Ismail Haniyeh in Gaza and the other by Salam Fayad in the West Bank. The parties remain divided, as negotiations aimed at forming a unity government have been unsuccessful. Meanwhile, some Palestinians, particularly Hamas leaders, argue that President Mahmoud Abbas’s term as president of the Palestinian Authority actually expired in January 2009.

Israel, the United States, and most of the international community responded to Hamas’s military and political victories with a policy of isolation. They vowed not to talk to Hamas until it affirmed Israel’s right to exist, renounced the use of violence, and accepted past Israeli-Palestinian agreements. Hamas declined and called on Israel to first withdraw to the 1967 borders and accept the return of the refugees.

Ostracizing Hamas meant that Israeli negotiations with the Palestinians were limited to Abbas and Fatah. Thus, the Annapolis process that the Bush administration launched in November 2007 led to talks between Olmert and Abbas; U.S. training of Palestinian security forces excluded Hamas personnel; and former British Prime Minister Tony Blair’s work on Palestinian institutions and economic development focused primarily on the West Bank.

Hamas will need to be part of any two-state solution. Hamas is one of the two strongest actors in Palestinian society, and it appears to be growing. But Hamas has never explicitly accepted the two-state approach.

There seems to be a growing awareness among international actors of the need for direct engagement with Islamist groups, including Hamas.

Might Hamas support a two-state solution? Khaled Meshal, the Damascus-based leader of Hamas, recently told The New York Times, “I promise the American administration and the international community that we will be part of the solution, period.” Hamas’s willingness to fight Israel has to some extent built its popular support, and it has largely remained outside the negotiations by arguing that Abbas and Fatah are Israeli puppets in the peace process and that talks have yielded few tangible gains. But if the center of Palestinian politics moves unequivocally behind a two-state solution, Hamas would risk its political standing by defying that shift. That may be one key to diplomatic success: to create a scenario in which spurning the peace process will be seen in a highly negative light by the Palestinian public and thus force Hamas to choose between defiance and political power.

If Hamas were willing to join, the other side would of course need to accept Hamas into the process. Thus far the Obama administration has not signaled any major change in policy toward Hamas. But it did ask Congress to change the law to allow U.S. funds to go to a hypothetical Palestinian unity government that included members of Hamas, and several members of Congress, including Senator John Kerry, have visited the Gaza Strip. At the same time, Israel is negotiating with Hamas through third parties such as the Egyptian government. And some members of the European Union have called for a move away from isolation. Britain’s recent renewal of talks with the political wing of Lebanon’s Hezbollah may indicate a growing awareness among international actors of the need for direct engagement with Islamist groups, including Hamas.

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If the two-state solution is frustrated by apparently intractable conflicts and political fragmentation, three other options are available: managed uncertainty, a Greater (and undemocratic) Israel, and a single binational state.

A first approach would be to try to continue managing the state of uncertainty that has lasted for more than 40 years. Without hope of resolution, perhaps managing the status quo–proceed with talks, occasionally reach partial agreements about nuts-and-bolts issues–is the best we can expect. Rather than focusing on resolving the conflict and detailing plans for doing so, making minor improvements and containing violence would be the more immediate goals. U.S. officials would try to build trust between Israelis and Palestinians and improve the Palestinian economy while promoting better governance.

That may sound much like the two-state approach, and there is overlap. But while efforts at economic and security improvement would continue, the emphasis and rhetoric would shift. There would be no time table for or expectation of resolving final-status issues such as the future of Jerusalem or refugees. There would be no grand plans or detailed blueprints. The time frame would be generational, with the hope that the situation would not get worse and might get marginally better.

This idea of managed uncertainty seems to resonate with some Hamas officials, who have talked of a long-term truce, a hudna, rather than an end-of-conflict agreement. Upon taking office as Palestinian prime minister in 2006, Ismail Haniyeh told a U.S. newspaper, “If Israel withdraws to the ’67 borders, then we will establish a peace in stages.” Phase II of the Roadmap, the peace plan released in 2003 by the Quartet (the United States, Russia, the European Union, and the United Nations), called for a Palestinian state with provisional borders, though the Quartet saw this as a stepping stone toward a permanent two-state solution. In general, measures would be partial, small, and temporary. Nathan Brown, of the Carnegie Endowment for International Peace and George Washington University, recently proposed shifting to “Plan B,” a cease-fire that could be developed into an armistice.

Managing the conflict may mean overseeing the continued growth of instability, war, and other factors that put a long-term solution out of reach.

While apparently less ambitious than a two-state solution, this strategy, nonetheless, carries large risks. One is that war could intensify or spread, or that the number of casualties and displaced persons could climb rapidly. Moreover, a project of conflict management runs up against past experience. Trying to keep the conflict at a low boil has not worked well; military confrontations have grown more destructive over time. While the first twenty years of the Israeli occupation, 1967-1987, were relatively quiet, the last twenty-plus years have seen increasing violence: the first intifada, the second intifada, Operation Defensive Shield (2002), and the Israel-Gaza war (2008-09). Small gains in trust and goodwill have been overwhelmed by national-level confrontations–every hesitant step forward has been matched by two painful steps back. So rather than managing the conflict until the situation is ripe for real improvement, managing the conflict may mean overseeing the continued growth of instability, war, and other factors that put a long-term solution out of reach.

A second alternative would be a more formal outcome: a Jewish, non-democratic state. The longer the two-state process goes remains unsuccessful, and the more Israel becomes entrenched in the West Bank, the more likely we are to see a single, non-democratic state as the de facto endpoint.

In the 2009 Israeli election campaign, Avigdor Lieberman, leader of the Yisrael Beiteinu party, proposed a loyalty oath to Israel as the Jewish state, exactly the type of measure that would suggest a transition from democracy to non-democracy. It would allow Israel to formally relegate Palestinians and some Haredi Jews to a different status if they refused the oath, while placing the blame squarely on the Palestinians and Haredim themselves. It would also ensure that the state’s identity as the Jewish state was locked in place.

Mustafa Barghouthi, a member of the Palestinian legislature and former presidential candidate, commented after the Israeli election: “If we continue down this path much longer, ‘no solution’ will manifest itself in the death of the two-state dream and continued Apartheid for the Palestinian people.” Israel could formalize the status quo and end up with a single state in which Israeli citizens and non-Jews who declare their loyalty to the Jewish state would be the only political actors with full rights. One variant is a proposal from the Israeli far right that calls for annexing the West Bank and giving Jordanian citizenship to the West Bank Palestinians; the Hashemite Kingdom of Jordan considers such ideas an existential threat and will do everything in its power to thwart them.

Should the United States support a non-democratic, one-state outcome, whether it emerges by default or by design? Such an endpoint conflicts with American values and certainly undermines a common rationale for the Israeli-U.S. alliance: shared democratic norms. But the United States has long been comfortable with non-democratic allies, including Egypt and Saudi Arabia. As long as the United States views Israel as a strategic ally and as long as Israel has a strong contingent of support in the United States, its position as a close U.S. ally is likely protected.

But U.S. acceptance of a non-democratic one-state solution would come at high cost. It would end any hope of resolving the Arab-Israeli conflict, as Palestinians would continue to fight. In the Arab and Muslim worlds, Israel and Israeli-U.S. ties would continue to fuel anti-Americanism. At best, the United States might be engaged in an internal peace process that aimed to improve the plight of Israel’s many Palestinian non-citizens. At worst, Palestinians would launch an uprising, and terrorism and other violence would spin out of control. The conflict would change in name only, with Palestinians and Israelis engaged in the same battles, this time inside a formally expanded Israeli state.

A third option is a democratic, one-state solution: if the two peoples cannot separate, then they must share in a binational state in which Jews, Palestinians, and other peoples are equal citizens. With almost every major player committed to a two-state solution, the likelihood of reaching a one-state, binational solution is vanishingly small. But what seems obvious today might give way suddenly and without warning, so it is worth describing the one-state solution.

Israel would almost certainly end up protecting its Jewish identity rather than its democratic character.

The idea of a single, binational state has been around since the early days of the Zionist movement. In the last few years, Palestinian interest in the idea has grown, especially among elites. Palestinians who despair of ever removing Israeli settlements look at a binational state as a way of leveling the playing field; demographic growth favors the Arab side and demographic advantage would presumably translate quickly into political power and Palestinian control. Some Palestinian advocates see democracy as the right moral choice while others see it as a strategically useful argument to create political pressure inside Israel for a less-radical change that would result in a separate Palestinian state.

Finally, the idea is attractive to Palestinians because “one person, one vote” has significant appeal to the United States. The Palestinians could drop violent resistance–itself a step that would make the Palestinian cause more amenable to U.S. policymakers–and become a civil rights movement demanding full, democratic rights.

For these reasons, most Israeli Jews would vehemently oppose a single, democratic state as the solution to the Israeli-Palestinian conflict. A large majority of Israelis want to preserve Israel as the Jewish state, an idea that is incompatible with a Palestinian majority. Israel will not willingly concede such a point. Israel would almost certainly end up protecting its Jewish identity rather than its democratic character. In short, the pathway to a one-state solution is very hard to discern given Israeli Jewish opposition.

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The United States could accommodate itself to any of the three options detailed above. Still, the two-state approach has a few clear advantages over the alternatives.

The Obama administration has set two states as a goal. And it has the support of many other actors both inside and outside the region, including the rest of the Quartet, the Arab League, the Palestinian Authority, and some of Israel’s major political parties (Kadima and Labor). Moving the key players to a different solution would be a monumental if not impossible undertaking. Meanwhile, Arab and Israeli fears about Iran may provide an impetus for Arab-Israeli resolution.

Furthermore, among the available options, only the two-state solution is a genuine compromise–both sides must make major concessions. With competing self-determination claims over the same territory and total victory for either side nearly impossible, the only way to realize both claims is to simultaneously narrow the territorial breadth of each, something many Israelis and Palestinians recognize.

So the two-state solution is deeply flawed, but it remains–in Churchillian spirit–the best hope and will likely hold that position for the foreseeable future. Its advocates have a very steep hill to climb.