The final horrific moments of Alton Sterling, 37, and Philando Castile, 32, have been watched and shared millions of times on Facebook and other social media. On July 5, Sterling was shot by police officers in Baton Rouge, Louisiana at least three times at point-blank range as he was pinned down to the ground. The next day, Castile was shot at least four times during a traffic stop in Falcon Heights, Minnesota, as his girlfriend and child watched helplessly. Both Sterling and Castile were African American.

Less publicized in the media were two other killings that underscore the pervasiveness of police violence in America, and the fact that it is not only African Americans who are targeted. On Thursday, a cell phone video was published by the Fresno Bee showing the police killing of 19-year-old Dylan Noble in Fresno, California on June 25. Noble, who was white and unarmed, can be seen lying on the ground motionless as police fire multiple bullets downward into his motionless body. This past weekend, police in Fullerton, California shot and killed 19-year-old Pedro Erik Villanueva, a Hispanic youth who was also unarmed, after a car chase.

The killing of Sterling and Castile, like almost all of the other 600 police killings that have taken place so far this year, and the thousands since the Obama administration took office, would have been “swe[pt] in the dirt” (to use the phrase of Quinyetta McMillon, the mother of one of Mr. Sterling’s children) had they not been recorded by bystanders on cell phone cameras.

It is now nearly two years since the killing of Michael Brown on August 9, 2014 sparked nationwide protests against police violence. However, despite the pledges of “reform” and cynical professions of concern from the political establishment when one or another killing sparks protests, the reign of violence continues unabated. Indeed, the number of killings so far this year exceeds the number of Americans killed up to this point in 2015.

Certain conclusions must be drawn. It is impossible to understand the epidemic of police violence without understanding the reality of American capitalism. The United States is characterized by vast and growing social inequality, in which mass poverty and joblessness coexist with the almost unfathomable enrichment of a financial oligarchy. While one in seven Americans falls below the official poverty line, 400 individuals control $2.34 trillion dollars.

The same ruling class that is waging a relentless war on the working class is engaged in unspeakable violence all over the world. Domestic and foreign policy are not separated by an iron wall. The methods used abroad are increasingly being deployed to deal with the social crisis at home. Within the overall apparatus of state repression, the police, armed to the teeth with the most modern weaponry, play a central role.

Police violence is essentially a class question. Understanding that opposition to police violence threatens to become the catalyst for a broader mobilization of the working class, politicians and the media have rushed to present the killing of Sterling and Castile as motivated exclusively by racism.

Racism no doubt plays a role in many police killings. However, the claim that police violence can be solely explained in racial terms is self-contradictory and untenable. While African Americans are disproportionately victimized by of police violence, half of those killed by police are white, according to an analysis by the Washington Post. In many cases, such as in the killing of Freddie Gray in Baltimore, the officers themselves are black or Hispanic. In some cities with the worst police violence, such as Baltimore and Philadelphia, a majority of police officers are minorities, and local governments are headed by black police chiefs, black city council members and black mayors.

Perhaps most significantly, the unending stream of police murders has taken place under the presidency of Barack Obama, an African American. The Obama administration has used federal investigations to whitewash police killings, has sided with the police in every use-of-force case brought before the Supreme Court and continues to oversee the transfer of military weaponry to local police forces throughout the country.

The Obama White House presided over the deployment of militarized police and National Guard to crack down on demonstrations in Ferguson, Missouri, in 2014 and Baltimore, Maryland last year following the killings of Michael Brown and Freddie Gray.