In a classroom at the University of Haifa in late December, Yitzhak Cohen, a fourth-year law student, began the shoulder-shrugging, arm-contorting choreography familiar to any student trying to remove a backpack.

But instead of a knapsack, Mr. Cohen, 28, a reservist who had recently returned from fighting in Gaza to attend the university’s orientation, unshouldered his military-issue Tavor assault rifle and took a seat in the back of the class.

Nearly three months after the outbreak of war delayed universities’ start dates, students returned on Dec. 31 to campuses in Israel for an abridged semester. Amid the usual first-day jitters, students and faculty were additionally anxious about resuming classes during a war that had unsettled the country, Jews and Arabs alike.

At the University of Haifa, a uniquely mixed institution where more than 40 percent of students are Arabs, those anxieties are amplified by what is among the school’s proudest achievements — its diversity.

For the first time since the outbreak of the war, Jewish students, some of whom had spent the past months fighting in Gaza or lost friends and family in the Hamas-led attack on Oct. 7, rubbed shoulders with Arab students. And some of those Arab students had relatives killed in Gaza or had been targeted and silenced on social media because of their views on the war.

While the fighting in Gaza is almost 100 miles away from the university, thoughts of the war are inescapable. About 1,500 military reservists attend the University of Haifa, and as long as they’re called up, the student-soldiers, including Mr. Cohen, are required to keep their weapons on them at all times. As a result, the newly armed students are bringing semiautomatic rifles to class.

“We’re doing everything possible to connect to our students and allay fears that people have,” said Ron Robin, the university’s president. That included focus groups intended to gauge students’ feelings before the start of the semester; Arab and Jewish professors talking with students and each other about the importance of diversity and inclusion; and holding many more meetings via Zoom.

Still, fears persist. More than 50 percent of Jewish and Arab students across the country are afraid of sitting in a classroom with one another, and nearly one in two Arabs have considered not returning to campus at all, according to a November survey by the aChord Center, a nonprofit that focuses on ethnic relations in Israel.

Situated on a hill overlooking the port city of Haifa, the university is dedicated to a mission of encouraging students to embrace a shared society, Mr. Robin said. On a windy December day, two female students wearing army uniforms, M16s slung over their shoulders, carried plastic bags filled with dorm-room supplies, while a first-year student wandered the corridors looking for his classroom. A few women wearing hijabs gathered around a picnic table.

Nicole Rashed, 21, a Christian Arab citizen of Israel, said that a key concern among Arab students returning to campus was whether their freedom of speech would be curtailed. Since the Oct. 7 attack, in which nearly 1,200 people were killed, according to the Israeli authorities, the University of Haifa has temporarily suspended nine students who administrators said had made pro-Hamas posts on social media. Mr. Robin said that the students were still under disciplinary review and that the university was trying to reach a compromise to drop the charges.

In light of the suspensions, some Arab students said they worried that if they made comments condemning the war, it could end their academic careers.

“Arab students think that if I post about a dead baby in Gaza on my story, they will stop my studies,” Ms. Rashed said. She does not believe the university plans to be so draconian, she added, but she is wary of making posts about the war on social media.

Ms. Rashed noted that she strongly condemned Hamas’s atrocities on Oct. 7 and understood Israel’s need to defend itself. But she is equally critical of the mounting death toll in Gaza, where, according to health officials there, more than 22,000 people have been killed.

“Speaking about the conflict is very complicated because you have to speak perfectly,” Ms. Rashed said. But, she added, the perfect sentence does not exist, “so I would rather not say anything.”

What most frustrates Ms. Rashed is the feeling that she always has to go above and beyond to prove that she does not support terrorism just because she is an Arab. “It sucks,” she said.

Asad Ghanem, a political science professor at the university and a Palestinian citizen of Israel, said he felt that, even before the war, the university took few “measures to let Arab students feel at home.” Oct. 7 and its aftermath, he said, have exacerbated those feelings.

He said he worried about being attacked by students who did not agree with his views, which are critical of both Israel and Hamas. In October, he said, several students threatened him with violence.

“I have to be more careful,” Dr. Ghanem said, explaining that he planned to set strict guidelines for his seminar this semester on the Israel-Palestine conflict. He is prepared to cut short debates to ensure heated discussions do not escalate.

The Israeli students have their own fears. Daniel Sakhnovich, 24, a freshman planning to study economics and Asian studies, said he was worried that some of his classmates supported Hamas and believed the wanton nature of the Oct. 7 atrocities was justified.

“You don’t know what’s going on in other people’s minds,” he said.

And like many students starting at the university, he was concerned that tensions on and off campus would make for an especially difficult first year.

“Everyone always says, ‘Oh, I met my best friends in college,’” Mr. Sakhnovich said. “I’m worried I won’t have that.”

Mr. Cohen, the reservist finishing his law degree, said he was aware that maintaining his social and academic life this year would most likely come second to protecting his peers’ actual lives. As the war in Gaza persists and tensions flare up along the Lebanese borders and in the West Bank, he said he felt an added responsibility to protect his classmates should there be an attack on campus.

Even so, “It’s not much fun to come to class with this gun,” Mr. Cohen said about the assault rifle on his lap. “It’s heavy.”

As he sat in the back of a lecture hall surrounded by classmates, the war for a moment felt very far away.

“I think the best treatment for the shock and post-trauma is a return to normal,” he said.

But then, in the middle of the orientation lecture, he received an urgent call from his commander: “Return to base, now.”

Mr. Cohen shouldered his rifle and left campus.

His return to normalcy would have to wait a bit longer.