David Makovsky, the Ziegler distinguished fellow at the Washington Institute and co-author with Dennis Ross of the book “Be Strong and of Good Courage: How Israel’s Most Important Leaders Shaped Its Destiny.

Israeli Prime Minister Benjamin Netanyahu is preparing to annex territory in the West Bank. He has set the date of July 1 for a cabinet vote on whether to apply Israeli sovereignty to parts of the area. Annexation has long been a taboo. It has never been endorsed by any U.S. administration, as it goes against the foundational idea of the peace process that territorial changes in the West Bank must be part of a negotiated solution. Yet now Israel is vowing to press ahead — with the apparently unqualified support of the Trump administration.

The crucial details are not yet final. But the peace plan proposed by President Trump’s administration this past January suggests that the action could encompass up to 29 percent of the West Bank and all 130 Israeli settlements there (including 15 Israeli enclaves within a Palestinian state). The remainder is set aside for a Palestinian state based on strict conditions. Netanyahu has embraced the plan as historic while Palestinian Authority President Mahmoud Abbas has slammed it.

Just a few years ago, the idea that Israelis might embrace annexation seemed extremely improbable. So how did we get here?

The fundamental problem is that, over the years, Israelis have ceased to believe that a negotiated peace with the Palestinians is possible. The hope of the 1990s and the famed Oslo accords exploded with the Second Intifada, the Palestinian uprising in 2000-2005, which killed more than 1,000 Israelis (and over 3,000 Palestinians), neutralizing the arguments of the Israeli peace camp.

After all, the premise of peace for Israelis was that territorial concessions would make them more secure. Yet Israeli unilateral pullouts from Lebanon in 2000 and Gaza in 2005 were met with fresh rocket attacks from Hezbollah and Hamas. The Palestinian Authority, which Israel had counted on to rein in Hamas, suddenly had no foothold in Gaza. Three U.S. efforts (in 2000, 2007-2008 and 2013-2014) failed to produce resolution on the core issues, deepening the sense that peace is unattainable.

The Israeli right was also strengthened by demographic shifts. The birthrate of the ultra-Orthodox and national religious continued to grow while secular Israelis had fewer children. Plus, young voters whose parents came from Mideast countries and the former Soviet Union became key to the ruling, right-wing Likud party. Now, Netanyahu has become even more politically indebted to the Israeli right, as they have taken his side in his court case on three charges of corruption.

An emboldened Israeli right gave a stronger voice to the settlers. There are now 466,000 Israeli settlers living in the West Bank. The settlers were never monolithic, even if many viewed the land as biblical patrimony. Many of those living closest to Israeli urban areas wanted a negotiated peace that kept them inside the proverbial tent. They are now united with the more ideological settlers who opposed a peace deal and view annexation as ending the limbo status of the land.

Additionally, in the past several years, the Palestinian issue has become less central in Israel and in the Mideast. The success of the security barrier built to halt Palestinian militant infiltration into Israel has made the Palestinian issue far less urgent. Moreover, despite Israeli-Palestinian security cooperation, Netanyahu has been able to cite Palestinian statements approving “martyrdom” against Israelis as evidence for the lack of a “peace partner.”

Several key Arab regimes are no longer giving the Palestinian issue primacy as in the past. Domestic and economic challenges as well as other regional hot spots have become more urgent. Israel has become more attractive to the Gulf states due to their common interest in thwarting Tehran and obtaining Israel’s cutting-edge technology. To be sure, security and economic cooperation remains hidden, but the Palestinians can no longer exercise a veto over whether such contacts exist.

The final factor is Trump. Having a partner in the White House who approves of annexation makes the move almost irresistible. The possibility that Trump could lose in the next election has only added urgency to Netanyahu’s agenda.

Even so, there is still widespread opposition to the annexation, and this could shrink its scope or even lead to postponement. If Israel annexes the Jordan Valley — located in the east of the West Bank, adjacent to Jordan — that could fray its ties to the Arab states; Jordanian officials have made it clear that such a move could prompt them to freeze their peace treaty with Israel. Key pillars of the security establishment believe that close ties with Jordan are more important than annexation.

Meanwhile, Netanyahu’s own coalition partner, the centrist Blue and White Party, is concerned about security cooperation with the Jordanians and the Palestinian Authority. Many worry that annexation will lead to the demise of the Palestinian Authority and erode Israel’s identity as a Jewish and democratic state. The European Union, Israel’s biggest trading partner, remains strongly opposed to annexation. And some Israelis worry that annexation would doom bipartisanship in the United States, which has been traditionally crucial for Israel.

The unthinkable is possible, but not yet inevitable.

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