A few months ago, the American Jewish community was thrown into a period of prolonged navel-gazing by journalist Peter Beinart.

Writing in the New York Review of Books, Mr Beinart claimed that right-wing American Jews had hijacked Zionism. He said their hawkish, Israel-can-do-no-wrong attitude was distancing liberal Jews, particularly the young, from Israel.

Now, Brandeis University has issued a rebuttal. Titled, Still Connected: American Jewish Attitudes about Israel, the Brandeis report takes direct aim at Mr Beinart's thesis.

Comparing the results of a survey of about 1,200 US Jews conducted in June with American Jewish Committee surveys over 24 years, the team of Brandeis researchers found that US Jewish attitudes towards Israel remain largely unchanged.

Their report admits that younger Jews, in their twenties and thirties, do have less attachment to Israel than their elders. But it suggests that the difference can be explained by lifecycle stage rather than a generational shift in attitude.

The report concludes: "Age differences are not new, and most likely indicate that attachment to Israel increases over the life course rather than declines across the generations."

Brandeis professor Leonard Saxe, a member of the research team, said: "He's [Beinart's] not on solid ground with respect to available data."

Such a conclusion is not accepted by Steven M Cohen, of Hebrew Union College, who has conducted similar research.

Professor Cohen said studies of young Jewish people show that "unpopular Israeli policies" cause detachment from Israel. He added that even the latest Brandeis data showed the gap in detachment between young and old is sharper today that it was 20 years ago.

However, professors Cohen and Saxe do agree on a few points.

They both say that political ideology has little to do with attachment to Israel. Liberal and conservative Jews are just as committed to Israel. The difference lies in their views on subjects such as settlement building and the Israeli-Palestinian conflict.

They also agree that a major cause of detachment is the rising intermarriage rate. A recent Brandeis study showed that free trips to Israel for young Jews, run by Taglit-Birthright Israel, appeared to increase Jewish engagement and to reduce the likelihood of intermarriage.

"Looking towards the future, it's a race between intermarriage and Birthright," said Prof Cohen. "Will travel to Israel turn younger American Jews towards Israel? Or will intermarriage turn them away?"

Mr Beinart, meanwhile, said his views have not changed fundamentally. He said that data in the Brandeis study appeared to support a number of his conclusions. And he noted that the Brandeis study included strictly Orthodox Jews, whereas his essay concerned non-Orthodox Jews.

He said: "I feel as confident as I ever have that this phenomenon is very much occurring and is masked a little bit in this study because it doesn't break it out between Orthodox and non-Orthodox Jews."