A new document has popped up in America, which some are calling the modern version of the “Protocols of the Elders of Zion.” It proposes a bad scenario whose essential core carries an updated all too familiar ring: “America is in this Iraqi war mainly to save Israel, not America, and has been manipulated to do so by the American Jewish lobby.”

The specter of “dual loyalty” rides again, especially disturbing as the news from Iraq worsens and popular support of the war declines daily. One possible consequence, among others, is that both Israel and American Jews could end up as major targets of the American public’s anger.

This study is not a screaming flier from one of the usual crackpot corners, but a “scholarly-style” attack on the “Israel Lobby and American Foreign Policy,” written by two reasonably weighty professors of political science at the University of Chicago (John Mearsheimer) and Harvard (Stephen Walt), and published this March by the John F. Kennedy School of Government at Harvard.

Nevertheless, it turns out to be about as scholarly as “kosher-style” food is kosher, and is a dangerous blueprint for the bad scenario.

But to just call the professors or their product “anti-Semitic,” as so many critics are now doing, is too easy. If we just let it go at that, we are missing the real dynamics of contemporary anti-Semitism and the kind of counteraction it requires.

The two professors/authors would surely have no truck with David Duke or his like. They would probably join us on the barricades to fight against any insurgent army of neo-Nazis. This document of theirs explicitly opposes anti-Semitism and Holocaust revision. But that is exactly why it is such a model of the kind of contemporary thought that could put American Jews in jeopardy.

Consisting of 80 packed pages, followed by over 200 footnotes, their paper is destined to serve as a sourcebook for several levels of the wrong- or weak-headed. David Duke, the well-known Klan member and anti-Semite, already has applauded it.

The main point this document strives to make is not about the Jews, but about the evil-doing of America in Iraq and in the Middle East in general. It is a coda to the article these same professors recently wrote about the Iraqi war, entitled “The Unnecessary War.” In order to make their point, they turn the whole Mideast war on its head, holding that the central cause is the “repression” of the Palestinians by Israel. That again puts the burden on America for supporting Israel.

The seminal and crucial failure of these professors is that they do not understand (or want to understand) what this Mideast war, including its Iraq sector, is all about, and why it threatens the West and America.

This war has been mounted by the radical Islamist movement and its agenda — the leaders of this movement were never much concerned about the Palestinians. A couple of weeks after 9/11, Abdul Rahman Al-Rashid wrote in a Saudi newspaper “never have I seen any reference [by bin Laden] to a political demand related to the occupied territories.” An Egyptian columnist sympathetic to al Qaida explained, “The conflict that we call the Arab-Israeli conflict is in truth an Arab conflict with Western and particularly American colonialism.”

These professors try to explain everything in terms of the Israeli-Palestinian conflict and America’s support of Israel. But although they try, scholarship does not sustain this explanation.

They fall all over themselves trying to put the major fault on Israel, ignoring or distorting many pages of history. The last refuge of the clueless is conspiracy theory, to which the professors lend themselves: America’s involvement in the Middle East results from the trickery of the American Jewish establishment.

Of course, conspiracy theorists on the far poles of both left and right already have proposed such a scenario — without much effect. According to all measurements, support for Israel has not eroded among the American mainstream, nor has there been a rise in the historically low level of anti-Semitism in this country. But this document does remind us that we should not be too carefree about the possible growth of a bad scenario, if worse comes to worst in Iraq and the Middle East.

This bad scenario, spun out of faulty logic and tattered scholarship, can have dangerous consequences for America, Israel and American Jews — if the Iraqi situation deteriorates beyond redemption and the American public washes its hands of the entire matter.

In addition, whatever the intentions of its authors, this document can become a classic example of how anti-Semitism can be enabled without being explicitly promoted. Counteracting this kind of bad scenario requires not just opposition to anti-Semitism. It requires us to help make clear that Americans have a major stake in effectively stopping the special agenda of the radical Islamic movement, which threatens American national interest along with that of Israel.

Earl Raab is director emeritus of Brandeis University’s Nathan Perlmutter Institute for Jewish Advocacy. He is executive director emeritus of the S.F.-based Jewish Community Relations Council.