An Israeli flag flies in Israel on March 17, 2013. (Ronen Zvulun/Reuters)

Last week the Pew Center released a survey of Israeli Jews. Coupled with its 2013 survey of American Jews, it provides an interesting portrait of how these two large Jewish communities compare — and how they feel about each other. Looking solely at the numbers, all appears to be reasonably well in the Jewish family. Yet a little historical perspective brings a very different angle to the present.

The differences are starker than surface appearances suggest; indeed, American Jews and Israeli Jews — without too much exaggeration — might be characterized as brothers from different planets (something I demonstrate in my book, “The Star and the Stripes: A History of the Foreign Policies of American Jews”).

Many of the differences between American and Israeli Jews can appear to be differences of degree rather than kind. Pew provides evidence of strong bonds between these two communities. Each is deeply proud of its Jewish heritage. American Jews overwhelmingly feel attached to Israel, including those who have never visited. Israeli Jews strongly identify with American Jews and welcome their involvement in Israeli life, and nearly the same percentage of Israeli Jews have visited the United States as American Jews have visited Israel.

Pew also tells us that American Jews tend to be better educated, older, more liberal, more secularized and less devout than their Israeli Jewish brethren. American Jews have a more optimistic picture of the possibility of a two-state solution and are more likely to see the settlements as an obstacle to peace. Another difference between the two is that American Jews are more likely to see ethics and social justice as essential to being Jewish. Differences, to be sure, but the sort of differences expected within any large family.

Surveys such as Pew’s can give an interesting, but highly partial, view for two significant reasons. Surveys are snapshots, providing a profile at a particular moment in time. But to make sense of the picture we need to put it into a broader context. We need to know the prior history.

Unfortunately, rarely are the same survey questions asked over decades to provide a historical context. Most of the available polls on how American Jews feel about Israel, for instance, begin after 1967, a year widely recognized as the moment that American Jews experienced a greater attachment to Israel. But what about the first two decades of Israel’s existence? And what about American Jewish attitudes to Jewish nationalism and Zionism, the forerunners to the state?

Another limitation with many of the surveys of American Jewish views of Israel is that they tend to ask fairly straightforward “yes or no” and “more or less” questions, which means that what might be rather complex feelings become simplified. Asking American Jews if they are pro- or anti-Israel isn’t going to generate much information. When American Jews are asked to answer preset questions about their attitudes, they tend to give answers that suggest a highly positive outlook. However, when American Jews are given a chance to talk, it becomes clear that their feelings are much more complicated. For my new book, I had hundreds of interviews and conversations with American Jews from all different backgrounds: rich and poor, young and old; orthodox, conservative, reform and unaffiliated; Republicans, Democrats and independents; religious and community leaders; and students. What I found was that American Jews are largely attached to Israel, but also highly ambivalent.

The ambivalence in the American Jewish community is not a new development. It has waxed and waned ever since the idea of a Jewish state first became seriously discussed in American Jewish circles in the late 19th century. The 1967 Six-Day War is when most American Jews cast aside their ambivalence, becoming the highly attached community they are now rumored to have always been. But since the 1990s, we have seen the return of ambivalence, suggesting that the current period has much in common with the pre-1967 period.

Why do American Jews feel ambivalent or conflicted about Israel? Survey findings tend to focus on Israel’s treatment of the Palestinians, settlement expansion, engagement with the peace process and tolerance for non-Orthodox Jewry, the Judaism practiced by a majority of American Jews. In other words, they look at policies. But my research suggests that such hot-button issues tap into more basic foundational values of most American Jews. American Jews want an Israel that reflects their values — and assess Israeli policies through the prism of those values.

What are these values? Democracy. A civic nationalism in which all citizens can be part of the nation. And religious pluralism and the separation of the church and state.

For American Jews, these values are Jewish, and American — and a core part of their identity. American Jews increasingly worry that Israel does not have the same commitment to these values, creating a fundamental conflict within their core identity. Israel’s democracy is premised, by and large, on having a clear Jewish majority.

Surveys of Israelis suggest that when forced to choose between being Jewish or democratic, they will now opt for a little less democracy. This conception of Israel as a Jewish state operates in the tradition of ethnic nationalism, where membership is dependent on ethnic identity, and not in the tradition of civic nationalism valued by most American Jews. The conception of Israel as a Jewish state, with the state deeply involved in religious life and religious pluralism absent, similarly conflicts with American core values and principles.

None of these concerns are new. Since the very beginning of Zionism, American Jews have worried that a Jewish state was inconsistent with their values and would complicate their lives. A century ago, the American Jewish establishment opposed Zionism. As they grudgingly came to accept Zionism, they hoped the future Jewish homeland would have the same values that immigrant Jews were enjoying in their new homeland in America.

American Jews celebrated the birth of Israel in 1948, but many hoped and prayed it would be an Israel that reflected well on the American Jewish people, and openly worried that a Jewish state in a hostile neighborhood would become ultranationalist. To return to this conversation among American Jews about Zionism and the future Jewish state is to get a glimpse of the present, filled with attachment but also ambivalence. What had gone dormant in the immediate decades following the 1967 war has reappeared.

This ambivalence matters for understanding the present and the future relationship between American Jews and Israel. It tells us that the source of such ambivalence is to be found not in this or that policy, but rather a fundamental difference of what kind of Israel American Jews want. And it is not clear that Israeli Jews want the same things or have the same idea of what Israel should be.

This disagreement is not only a source of ambivalence of American Jews, but it also is a major reason for the growing split within the American Jewish community regarding Israel. Ask American Jews whether they feel attached to one another, the answer will invariably be yes. Try asking them how they feel.

Michael Barnett is University Professor of International Affairs and Political Science at the George Washington University and the author of “The Star and the Stripes: A History of the Foreign Policies of American Jews” (Princeton University Press, 2016).