More and more American Jews these days are critically engaging with Israel, over such issues as West Bank settlements, trading land for peace, and the nuclear deal with Iran.“There are really two Jewish Americans,” the journalist Peter Beinart has written.“One is older, richer, more Republican, more Orthodox, and more interested in shielding Israel from external pressure than pursuing a two-state solution. The other is younger, more secular, less tribal, overwhelmingly Democratic, less institutionally affiliated and more troubled by Israel’s direction.”In Trouble in the Tribe, Dov Waxman, a professor of political science, international affairs and Israel studies at Northeastern University, examines the widening divide among American Jews and its significance for US support for Israel in the future. Making good use of polling data and other sources, Waxman sorts out the spectrum of attitudes of American Jews; the fracturing of the pro-Israel lobby; the challenges faced by the American Jewish establishment; and a public debate that is now taking place at the extremes.Informative and judicious, if not always surprising, Trouble in the Tribe makes a valuable contribution to a topic that often summons up more heat than light.Waxman emphasizes that a substantial majority of Jews in the United States – especially those who are active in Jewish organizations – repudiate anyone who either challenges the legitimacy of the Jewish state, endorses a one-state solution to the Palestinian-Israeli conflict, advocates a Palestinian “right to return,” or supports boycotts, divestment or sanctions against Israel. Many American Jews are also “hawkish doves” in that they approve aggressive military action by Israel against Palestinian terrorists, including “targeted assassinations,” but favor the establishment of a Palestinian state and the dismantling of some Israeli settlements, and oppose a division of Jerusalem.There is no consensus, however, on these issues. Several polls indicate that about half of American Jews now oppose a Palestinian state. A significant minority, ranging from 35% to 45%, believe that settlements enhance Israel’s security, have no impact on the peace process, and should not be dismantled. What is different now, Waxman demonstrates, is the extent, frequency and stridency of criticism of Israel by American Jews – and the ferocity of the backlash against it.Feeding off each other, the Left and the Right “have gone viral,” with one side condemned as racist, colonialist, and fascist and the other as assimilated, self-righteous, self-hating Jews.Along with religiosity (or lack of it), Waxman points to age as a significant variable for the division of opinion among American Jews. Only a quarter of Jews aged 18-29 (compared to 43% of those over 50) believe the government of Israel is making a sincere effort to make peace with the Palestinians.A quarter of young Jewish Americans (compared to 5% of their elders) claim that US support of Israel is excessive.For younger non-Orthodox Jews, who have grown up in a country in which Jews are powerful and privileged, and have married non-Jews, Waxman suggests, solidarity with members of the tribe (and an “us versus them” worldview) has become passé. Indeed, only 30% of them think that “caring about Israel is essential to being Jewish.”Waxman does not expect an end to divisive debates about Israel among American Jews. He predicts higher barriers, less common ground, growing mistrust and a face-off that may pit Orthodox Jews against less-religious Jews. The differences between the two groups are already stark. Secular liberals, who are committed to human rights, equality and post-ethnic, multicultural societies, increasingly perceive Israel as a violent, oppressive pariah state. As their intermarriage rates skyrocket, moreover, their attachment to Israel may decline even more.For Orthodox Jews in the United States, whose numbers are growing (nearly half of Orthodox families have four or more children), support for Israel is a fundamental political litmus test. More loyal to the Republican Party than Americans overall, Orthodox Jews make common cause with evangelical Protestants on social issues, including abortion and gay marriage. While more than 70% of Jews voted for Barack Obama in 2008 and 2012, Orthodox Jews loathe him.Over time, Waxman speculates, in what for him is clearly a nightmare scenario, support for Israel might become “merely an Orthodox cause,” and a Republican, rather than a bipartisan, cause at that. Accompanied, almost certainly, by the defection of most non-Orthodox, liberal Jews, a sharp turn to the Right could weaken American Jewish political and financial support of religious pluralism in Israel, Arab civil rights, and an Israeli-Palestinian peace agreement. Such developments, Waxman warns, would “constitute a long-term threat” to consistent and enduring backing for Israel by the government of the United States, which – given the growing hostility toward Israel in the capitals of Western Europe and in the United Nations – is more essential than it has ever been. Glenn C. Altschuler is the Thomas and Dorothy Litwin Professor of American Studies at Cornell University.