I downvoted all the other answers, not a single one of which was by a Vietnamese and seem to be veiled excuses to air the authors’ bigotry. I feel obliged to address this important question because it deserves a more serious discussion than that.

While I am not a Vietnamese American myself, I have been following and engaging with this community online in the last 3 years, especially the recent coverage on BLM. While I have requested some Viet-Am on Quora to answer this question and I defer to them, I think I also have some insight to offer on this topic.

I found this poll from an old answer about Asian Americans’ attitudes towards BLM. This is a diverse community with varying levels of support but generally, the majority of Viet-Am don’t particularly care about this topic:

Conversations about police brutality and racism are currently reverberating throughout American society, spawning heated discussions not only in America but elsewhere. Just last week, I had a conversation with a Viet Australian friend who is struggling with this exact issue. She expressed her exasperation at her family’s racism and bigotry despite having lived in Australia for over 40 years.

The recent events have exposed a very deep generational divide among the Viet-Am community and the Vietnamese diaspora more broadly. Many young, progressive Viet-Am are trying and struggling to have this difficult conversation with their family about race and racism, an endeavour often fraught with tension and disappointment.

It seems to me that many Vietnamese and Vietnamese Americans are still apathetic and antagonistic when it comes to this issue. Reading and engaging in many conversations online has given me some idea of why it is the case. But first it is important to understand what racism means in the Vietnamese context.

Racism is a very charged label, which can range from apathy, prejudice, negative stereotyping, to more seriously, bigotry, suspicion, contempt, hatred, dehumanization, oppression, subjugation, violence and genocide. Racism in the Vietnamese context is more of apathy, prejudice and contempt than outright hatred and violence. Our history and culture can partly explain this mindset.

First, Vietnam is a fairly homogeneous country. 85% of the population are the Kinh who have held power throughout our history, at times by conquest and domination over other ethnic groups. The ethnic minorities live in remote areas with very little representation in the media or in our education. Most Vietnamese people have little exposure to or knowledge of our own ethnic minorities and have no experience of racial conflicts.

Further, we were continuously under oppression and at war for thousands of years. Much of our history was spent fighting foreign invaders, civil wars and struggling for survival. The threat of flood, famine, peasant uprising, poverty, invasions was constant. This produced a zero-sum game society that prized pragmatism, conservatism, order and stability.

The rigid hierarchical social structure based on Confucianism put a high value on submission and obedience to authority. The priority is self-preservation and indifference to wider social issues that don’t directly and immediately affect oneself. The ideas of ‘citizens’ with rights and demands on government and social activism are still fairly recent and unfamiliar concepts, an aspect of modernity thrown upon us by violent revolution and then quickly forgotten/suppressed by it. Even revolutionaries eventually revert back to their true cultural nature. Vietnamese people, used to the idea that you can be punished for speaking out, choose to be silent, resign to fatalism and ignore injustices that don’t impact them.

Against that broader cultural backdrop, Vietnamese Americans came to America ignorant of the history of systemic racism. They put their heads down and worked hard to build their new life and identity, rather oblivious and apathetic to the plight of African Americans. They seemed unaware that in 1978, when boat people were arriving in refugee camps in Southeast Asia, African-American leaders called for the U.S. to admit Indochinese refugees, amid much opposition from large swathes of the American populace. Their rights in America were the fruit of the struggle by black activism in the preceding century.

I believe that even after having lived there for decades, they still feel indebted to America and feel that it is not right to question her, like guests can’t criticise the host. You don’t bite the hand that feeds you, a tension commonly felt among first generation immigrants. To be accepted in this new society, they have adopted it with a fervent loyalty which they equate with being unquestioning, obedient, compliant citizens. By being silent on the issue of anti-Black racism, they are anxious to ingratiate themselves to whites and defend their tenuous toehold in American society.

The legacy of colonisation also left a deep mark on our psyche and I actually think there’s a subtle inferiority complex among our people. We claim to despise the West and white people for their exploitation of our land but we subconsciously also revere them. In this hierarchy, blacks are at the bottom of our sympathy. Like Paulo Freire wrote in Pedagogy of the Oppressed, “The oppressed, instead of striving for liberation, tend themselves to become oppressors.”

Others have internalised the myth of the model minority, that if they can succeed from nothing after escaping poor, war-torn countries, then surely African Americans can too. Blacks just need to work harder, stop being criminals, stop being lazy, go to school and they should succeed just like Asian Americans. They deny the existence of anti-Black racism, justifying police brutality by insinuating that blacks must have done something to deserve it. If only they just behaved obediently like us Asians, the problem would go away! Perhaps some feel resentful of all the affirmative actions they believe are designed to give Black Americans an unfair advantage and to discriminate against them. Animosity is further hardened by negative personal experiences and anecdotes of crime and violence.

In his recent Time article Asian Americans Are Still Caught in the Trap of the ‘Model Minority’ Stereotype. And It Creates Inequality for All, writer and professor Viet Thanh Nguyen eloquently elucidates this tension:

No longer the threat of the Asian invasion, we were, instead, the model minority: the desirable classmate, the favored neighbor, the nonthreatening kind of person of color.

Or were we? A couple of Asian-American students talked to me afterward and said they still felt it. The vibe. The feeling of being foreign, especially if they were, or were perceived to be, Muslim, or brown, or Middle Eastern. The vibe. Racism is not just the physical assault. I have never been physically assaulted because of my appearance. But I had been assaulted by the racism of the airwaves, the ching-chong jokes of radio shock jocks, the villainous or comical japs and chinks and gooks of American war movies and comedies. Like many Asian Americans, I learned to feel a sense of shame over the things that supposedly made us foreign: our food, our language, our haircuts, our fashion, our smell, our parents.

… we told ourselves these were “minor feelings.” How could we have anything valid to feel or say about race when we, as a model minority, were supposedly accepted by American society? At the same time, anti-Asian sentiment remained a reservoir of major feeling from which Americans could always draw in a time of crisis. Asian Americans still do not wield enough political power, or have enough cultural presence, to make many of our fellow Americans hesitate in deploying a racist idea. Our unimportance and our historical status as the perpetual foreigner in the U.S. is one reason the President and many others feel they can call COVID-19 the “Chinese virus” or the “kung flu.”

… Given our tenuous place in American society, no wonder so many Asian Americans might want to prove their Americanness, or to dream of acceptance by a white-dominated society… So long excluded from American life, marked as inassimilable aliens and perpetual foreigners, asked where we come from and complimented on our English, Asian immigrants and their descendants have sought passionately to make this country our own.

Asian Americans are caught between the perception that we are inevitably foreign and the temptation that we can be allied with white people in a country built on white supremacy. As a result, anti-Black (and anti-brown and anti-Native) racism runs deep in Asian-American communities. Immigrants and refugees, including Asian ones, know that we usually have to start low on the ladder of American success. But no matter how low down we are, we know that America allows us to stand on the shoulders of Black, brown and Native people. Throughout Asian-American history, Asian immigrants and their descendants have been offered the opportunity by both Black people and white people to choose sides in the Black-white racial divide, and we have far too often chosen the white side. Asian Americans, while actively critical of anti-Asian racism, have not always stood up against anti-Black racism. Frequently, we have gone along with the status quo and affiliated with white people.

The next point, potentially sensitive and controversial, is that I suspect some people, after great suffering, instead of becoming more empathetic and generous, can be consumed by a collective narcissism. Maybe it is a wound that has not healed, the trauma of losing one’s country, identity, feeling alienated from the new society and culturally disconnected from their Americanised children. Many older Vietnamese Americans believe that they deserved and were uniquely entitled to be helped by America, because America abandoned South Vietnam, unlike any other immigrant or minority groups today.

The final aspect is the cult of Trump, which runs deep among a significant fragment of the Viet-Am community. Trump has stoked up and encouraged ugly racist sentiments which his devotees now more overtly espouse. The confluence of all these factors above explain why so many Vietnamese Americans are unsupportive of BLM.

Despite all of this, I am in fact quite optimistic about the situation today. The younger generation understand that patriotism means being aware of injustice and standing up against it. They are starting to step out of the shadow of their elders and grow mature as a community with their own voice. The BLM movement has even impacted young people in Vietnam and inspired conversations about our relationships with our own minorities. These might be offshoots of change.

PS: I also recommend Jennifer Hu’s answer on a related question: Jennifer Hu's answer to Asian Americans, have you ever talked to your immigrant parents about racism towards black people? How did it go?