NEW YORK (NYTIMES) - In August, Mr Howard Wong, a Hong Kong native and graduate student at Baruch College in Manhattan, shared a social media post in support of the pro-democracy protests in Hong Kong. One of his friends from mainland China took offence.

"He immediately messaged me and said, 'We should just not be friends with each other anymore'," recalled Mr Wong, 24. "I said, 'Hold on, hold on. Let's talk about this'."

They did, agreeing to disagree.

But not all conversations around the city between young people from mainland China and Hong Kong about the protests have gone this easily. That is, if there have been any conversations at all.

What is lacking in discourse can be seen in more physical acts, however, like Lennon Walls (installations with messages of hope) in support of the protests mysteriously and repeatedly being torn down, counter-protesters singing and flying flags, and bottles getting thrown at marchers during protests.

There is tension on both sides: Some mainlanders feel as if they will be misunderstood for questioning the protests, while many Hong Kongers said they are questioning their cultural and political identities on deeper levels.

Over the past few weeks, as students from abroad returned to school in New York for the fall semester, there was concern that the protests would spill over onto campuses, which has happened in parts of Australia, New Zealand, Canada and in other United States cities such as Boston.

Signs of unrest have bubbled up at Columbia University, where a flier raising awareness about the protests was defaced with the message "trash teenager", a term used by Chinese government-sponsored media.

And just a few days ago, close to 20 protesters holding China's flag gathered at a Columbia lecture hall where Mr Joshua Wong, a recently incarcerated pro-democracy activist, and Mr Brian Leung, another activist known for removing his mask during a protest at the Hong Kong Legislature this summer, were giving a talk.

Following the panel, two young mainlanders stood up to sing the national anthem. News outlets in China covered the incident.

"Even in the daily life of students, Hong Kong people have to defend their right for freedom and democracy and still face a threat from Beijing," Mr Wong said of the effort.

On the other side, some students from mainland China said they are afraid to speak their minds, regardless of their opinions.

Ms Livi, 27, a mainlander who asked to go by her nickname and omit her last name and school for security reasons, was so anxious about returning to New York that there were nights when she could not sleep, she said. Imagining the prospect of having to confront people with different views was terrifying, she explained. What if she heard people saying negative things about China?

"Should I defend my country? Do I have the responsibility to do that? What would that make me feel, if I don't?" Ms Livi said. "It's a very troubling thought for me."

Ms Livi said that she has had civil discourse with some Hong Kongers. She does not agree with them - "I think the aspiration of democracy is noble, but the consequence is destructive or detrimental" - but she has enjoyed some "honest, heartfelt exchanges".

She is also hesitant to express her pride in being Chinese because she does not want to be called "nationalistic" or "brainwashed", she said. "They'll just punish you and say you don't know the truth."

A vast majority of Chinese students consume their news via WeChat, a popular messaging platform in China that the government censors and surveils - so much so that some have said their accounts were shut down for sharing information about the protests.

But by living in the West, students from mainland China are exposed to media that present a different side of the story. Some say they are trying to make sense of the conflict, now that many of them are experiencing pro-democracy points of view for the first time.

"I feel it's very difficult to tell which is right or wrong, which is truth or which is not," said Ms Judy, a mainlander student at Columbia, who spoke on the condition that her last name not be used. Fighting for democracy, she explained, continued to be an opaque concept for her.

This line of thinking strikes at the core of the conflict. Hong Kongers grew up with the notions of liberty, democracy and freedom of speech; ideas and experiences that are not promoted in mainland China.

And whereas some Hong Kongers were once accepting of being called "Chinese", they say it is different now. They want to distinguish themselves.

Ms Cheryl, 19, a Hong Konger who studies at New York University and who asked that her last name not be used, said being called Chinese means something very different from what it did just four months ago. Now, when people describe her as Chinese, Ms Cheryl said, she feels misrepresented, and she corrects them.

That sentiment was not always the case, particularly in the years following Tiananmen Square in 1989, said professor of biology Anna Yeung-Cheung at Manhattanville College and a Hong Kong native who has been an activist for more than 20 years.

"Back then, the mood was that we were Hong Kongers, but we were part of China," Prof Yeung-Cheung said. "The identification was not as clear."

Prof Yeung-Cheung is also the founder of New York For Hong Kong, or NY4HK, a group she established in the wake of the 2014 umbrella protests, which called for more transparent elections in Hong Kong.

The climate was different then, she said. The Umbrella Movement lasted 79 days and was mostly peaceful. The current demonstrations, now in their fourth month, have been marked by violence.

Over the summer, NY4HK organised several events in the city, including marches to the Chinese consulate and a flash mob in Grand Central Terminal, which went without a hitch. But at an August rally in Manhattan's Chinatown, Prof Yeung-Cheung said that her group was met by demonstrators who carried Chinese signs that read "Love China Love Hong Kong". There were also reports of water bottles being thrown at them.

This was a first for Prof Yeung-Cheung, she said. There have also been disruptions in other parts of New York. A Lennon Wall in Chinatown, one of several throughout the city featuring notes in support of the pro-democracy movement, had been vandalised and torn down several times.

"You see the division," Prof Yeung-Cheung said. "And it's a severe one."