The University of Michigan has faced a flurry of criticism from American Jewish groups and an Israeli cabinet minister, after two students were denied letters of recommendation to study in Tel Aviv and a guest lecturer compared Israeli Prime Minister Benjamin Netanyahu to Adolf Hitler.

In a letter sent to U-M President Mark Schlissel on Monday, Israeli Education Minister Naftali Bennett condemned the image of Netanyahu and Hitler, which was displayed on campus last week as part of a speaker’s series that was mandatory for some students to attend.

Bennett further pointed to a recent incident involving John Cheney-Lippold, a U-M professor who rescinded an offer to write a letter of recommendation for a student after learning she planned to study abroad in Tel Aviv.

“I feel the time has come for you as head of the university to make a strong stand against what has clearly become a trend of vitriolic hatred against the Jewish state on your campus,” the minister wrote.

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The Netanyahu-Hitler comparison also drew concern from the World Jewish Congress, which on Tuesday called it an unacceptable “display of antisemitism” and extended support to several Jewish students who are demanding that U-M adopt the International Holocaust Remembrance Alliance (IHRA) definition of the hatred.

The definition — endorsed in 2016 by more than 30 IHRA member countries, including the United States — includes “drawing comparisons of contemporary Israeli policy to that of the Nazis.”

Groups including the American Jewish Committee and the Anti-Defamation League (ADL) last week also condemned the incident and urged the administration to take appropriate action.

The ADL again shared its concerns on Tuesday, following news that a second U-M student who wanted to study abroad in Israel, Jake Secker, was denied a letter of recommendation.

Secker explained in a Washington Post interview that he requested the letter last Monday from a graduate student instructor, Lucy Peterson, who initially said she would be “delighted” to comply.

Yet after finding out that Secker sought to attend Tel Aviv University, Peterson said she “regrettably will not be able to write on your behalf.”

“Along with numerous other academics in the US and elsewhere, I have pledged myself to a boycott of Israeli institutions as a way of showing solidarity with Palestine,” Peterson explained in an email. “Please know that this decision is not about you as a student or a person, and I would be happy to write a recommendation for you if you end up applying to other programs.”

Secker, whose father is Israeli, said he contacted a board member of Michigan Hillel about the incident, and that his complaint was ultimately kicked up to the Board of Regents and Schlissel, the university’s president.

Rick Fitzgerald, a spokesperson for U-M, told The Algemeiner on Tuesday that as both parties in the case were students, the university was prohibited by law from disclosing any information.

He pointed to a statement passed by an executive faculty body at U-M last month, which urged professors to base their letters of recommendations on “student’s merit.”

“Faculty leadership is closely aligned with the university administration on the topic of faculty writing letters of recommendation,” Fitzgerald added.

Yet critics — some of whom have dismissed the statement as toothless — have continued calling for U-M to take stronger action.

Jonathan Greenblatt, head of the Anti-Defamation League, called Peterson’s conduct “absolutely disgraceful” on social media, adding in a statement that U-M “must take immediate steps to ensure that students are not denied an opportunity to participate in an accredited overseas program because of their professors’ political views.”

He applauded Schlissel for denouncing boycotts of Israel — a stance shared by the school’s regents, one of whom described Cheney-Lippold’s behavior as “antisemitic” — but emphasized that “more needs to be done.”

“Boycotts such as these, refusing to recommend a worthy student solely because she intended to study in Israel, have a chilling effect on Jewish and pro-Israel students on campus, who may feel isolated and vulnerable when authority figures or campus groups express hostility or shun them based on their views and associations,” Greenblatt continued.

He urged U-M and other schools to ensure that pupils are not thwarted in their studies by their professor’s personal political opinions.

“Certainly everyone, including professors, has a right to openly express their views of the policies of the elected Israeli government,” Greenblatt noted after affirming the ADL’s support for academic freedom. “But this should not be at the expense of students seeking to broaden their academic experiences.”

Efforts to single out Israel “alone among all the nations of the world as worthy of boycott” potentially cross the line “from criticism of Israel to anti-Semitism,” he warned, citing the US State Department’s working definition.

Last month, Tammi Rossman-Benjamin — director of the AMCHA Initiative, a campus antisemitism watchdog that led nearly 60 groups in condemning Cheney-Lippold — told The Algemeiner that “there are probably close to 2,000 faculty across the country who have endorsed some version of the academic boycott of Israel,” including at least two dozen at U-M, a number of whom serve in leadership roles within their departments.

Ten professors from various universities announced in a statement published last month that they, like Cheney-Lippold, do not write letters of recommendations for students seeking to study abroad in Israel.