In May 1970, National Guard soldiers fired live ammunition into a crowd of anti-war student protesters at Kent State University, Ohio. When the firing stopped, four students, all unarmed, lay dead.

In early February this year, mass demonstrations prevented a planned speech by right wing extremist Milo Yiannopoulos at the university campus in Berkeley, California. Dan Adamini, a prominent local leader of the Republican Party in Michigan, tweeted in response: “Time for another Kent State, perhaps”, and “One bullet stops a lot of thuggery”.

As Donald Trump and his team settle down to work, it’s not hard to see elements of a police state being assembled in the US. Exactly how far this push will get, in the face of various forms of resistance, is impossible to predict.

But a survey of the forces of repression marshalled by various arms of the US state shows Trump is building on strong foundations laid down by his predecessors. The US ruling class loves to proclaim the country “the greatest democracy in the world”. But the reality of law enforcement in the US shows that its power relies on a colossal level of coercion.

There are 18,000 law enforcement agencies in the US. These range from vast federal agencies such as the FBI, through to the police forces of the major cities, state troopers and county sheriffs, and down to dedicated law enforcement agencies for cities and small towns – and even for particular college campuses, small suburbs and transit systems.

Each one of these agencies can employ deadly force. And they do so regularly.

Exactly how regularly is hard to tell: no government agency bothers to tally the body count of those killed by police in the US. The figure that gained prominence from the Black Lives Matter movement – that every 28 hours a Black person is killed by a cop, security guard or vigilante – might be an underestimate given systematic under-reporting, especially from smaller towns.

Black Lives Matter exploded across the US after a white policeman in Ferguson, Missouri, shot dead unarmed Black teenager Mike Brown in August 2014. The killing of Mike Brown was one horrific incident in a long history of racism from the authorities in Ferguson – a mainly Black, working class suburb on the outskirts of St Louis.

Since that time, there have been many hundreds more killings. The pattern is familiar: an alleged minor misdemeanour, the police intervene, and deadly force is deployed.

Eric Garner is stopped for allegedly selling loose cigarettes in a New York street. He calls out “I can’t breathe” 11 times as police squeeze the life out of him in broad daylight on a Staten Island footpath.

Chad Robertson is one of three Black men stopped at a Chicago bus station, allegedly for smoking a joint. When he tries to flee, an Amtrak police officer kneels and takes careful aim, shooting the unarmed man dead.

Each of these killings, and each of the dead, has a story. But the story of the Ferguson police force, which murdered Mike Brown, tells us something about the whole set-up.

St Louis has a population of a million, and no fewer than 90 separate local governments – each with its own town hall, its own mayor and aldermen/women and its own police force. In the areas of St Louis such as Ferguson, investigations by journalists and the federal Department of Justice found that a big proportion of government revenue is simply extorted by the cops from the local population, especially Blacks.

Cops use trivial or made up offences – from wearing “saggy pants” to driving a clapped-out old car – to levy fines. Blacks too poor to pay the fines and too scared to go to court are then arrested for that “crime”, imprisoned and have new fines added. Many end up owing many hundreds of dollars more than the original fines, and are thus subject to arrest again. It’s a profitable and never ending racket for the local authorities and cops.

When the residents of Ferguson took to the streets to protest against the killing of Mike Brown and the racist policing behind it, the whole world saw how highly militarised US policing has become. In 2013 alone, $400 million worth of military equipment, used in the occupation of Iraq, was transferred to local police agencies. Armoured cars, tanks, body armour, grenade launchers and other assault weapons can now be deployed as a matter of course by local police forces dealing with any civil disturbance.

One veteran of the Iraq war observed that he had “served in one of Iraq’s bloodiest cities, during the most violent time of the war, with the same gear that a civilian police department is now using in the small American town of Ferguson, Missouri, to quell civic disturbances there. Our wars have come home”.

In the case of Ferguson, as in Iraq, it’s not difficult to see that physical force is essential for the profits of a ruling elite. This is no less true for other sections of the US state’s vast apparatus of repression.

The recent dispersal of the Standing Rock protest camp against the Dakota Access Pipeline involved local cops, sheriffs and deputies from neighbouring counties and states, the National Guard, company security guards with guns and dogs, and security industry mercenaries. They were armed to the teeth with guns, tear gas, tasers, rubber bullets and a 150-decibel sound weapon known as a Long Range Acoustic Device. The company behind the pipeline is now free to reap an estimated $1 billion per year in revenue.

The nationwide dispersal of the mass anti-austerity Occupy protests in late 2011 is another example in which the brutality of the US state was on public display, keeping the interests of the richest 1 percent secure. Organised workers are also subject to this sort of repression if they offend the interests of the rich and powerful. In the same year as Occupy, dozens of dock workers in Longview, Washington state, were arrested after an effective picket in defence of union jobs and conditions.

“They’re rounding us up like we’re murderers”, said Dan Coffman, president of the Longview local [union]. Five police dragged one union official out of his car by his hair, roughed him up, and slammed him into the back of a squad car. Another member was hauled away while caring for his children, two and seven years old, leaving them to fend for themselves in an empty house. Yet another, a part time minister, was arrested by police wielding assault rifles.

It’s not just flash points like this where large doses of physical repression serve the interests of the system. “Stop and Frisk” was the official policy of the New York Police Department between 2002 and 2013. During those 11 years, NYPD officers stopped and shook down citizens of New York an incredible 4.4 million times – peaking at over 600,000 stops in 2011. Overwhelmingly, the program targeted Black and Hispanic neighbourhoods.  This routinised brutality served a reactionary law and order political agenda, which helps keep ordinary people intimidated, divided, and “in our place”.

Spying is another means of achieving these ends. In 2011, a series of articles by Associated Press journalists exposed a six year, $3 billion spying and infiltration operation targeting various Muslim communities by the New York Police Department, in collaboration with the CIA. By the NYPD’s own admission, not a single lead or charge came out of the investigation. But it did succeed in intimidating many New York Muslims from protesting for civil liberties, discussing politics in public, putting Al Jazeera on in a cafe, attending a mosque or “looking Muslim” by growing a beard.

Police departments, large and small, are only one part of the vast apparatus of repression and surveillance that is the US state. There’s the Federal Bureau of Investigation, with a continuous track record in repressing left wing, anti-war and Black liberation movements since its origins as the “Radical Division” of the Justice Department in the late 1910s. The FBI’s COINTELPRO program led to the assassination of numerous members of the militant Black Panther organisation in the late 1960s and early 1970s, and FBI surveillance and repression against left wing movements continues through to today. Unsurprisingly, large swathes of the FBI solidly backed Trump during the election campaign, as did the union for Border Patrol officers.

Trump and his political machine see this vast repressive apparatus as a key base of support. In speech after speech, Trump goes out of his way to flatter law enforcement and security apparatuses and promise them new powers.

Under Trump, officers of the Immigration and Customs Enforcement bureau (ICE) have been given new powers, expanding the categories of undocumented migration facing deportation to include anyone who, “in the judgment of an immigration officer … poses a risk to public safety or national security”.

In many circumstances, ICE agents now feel emboldened to act as their own judge and jury, rather than being constrained by immigration courts or any other legal restriction. We can see the result at the border, as travellers ranging from Muslim teachers from Britain and Muhammad Ali’s son, through to Australian children’s author Mim Fox are stopped, interrogated and intimidated by agents let off the leash in the new political environment.

Another sign of this is the fate of Sara Beltran Hernandez, an asylum seeker from El Salvador. She was receiving treatment for a brain tumour when she was dragged out by ICE agents during a raid in late February, shackled hand and foot. “ICE and Border Patrol have not respected hospitals for years”, remarks undocumented immigration activist Aly Wane. But the few limits there were on who gets picked up and deported, are now being removed: “It is just open season now”.

Trump is keen to involve the widest layers of the US state in this sort of repression. Officials have floated proposals to involve the National Guard, a reserve military force numbering in the hundreds of thousands, in the detention of undocumented migrants. While these proposals seem to have been shelved for now, Trump is pressing ahead with efforts to enrol local police in immigration enforcement. His stated policy during the election campaign was to revive New York’s policy of “stop and frisk” and roll it out nationally.

It’s telling that the closing address of the recent Conservative Political Action Conference, the premier event of US conservatism, was given by reactionary Milwaukee sheriff Dave Clarke, who has made a reputation for himself – and sparked mass protests – by promising to crack down on immigrants and on the “movement of resistance” against Trump. (A “movement of protest”, says Clarke, voices dissent but accepts the right of authorities to continue their actions. A “movement of resistance”, by contrast, challenges that right – and is much more dangerous to the authorities.)

Clarke used his CPAC address to give a rallying call to the sort of local law enforcement seen in Ferguson, St Louis, and far beyond, couched in terms of “self rule” of local communities, as opposed to being “ruled from a throne room or a centralised government”.

Republican officials around the country are pushing a similar agenda – with repressive anti-protest laws being bulldozed through various state legislatures, along with dozens of proposed “blue lives matter” laws, which turn any offence against a cop into a “hate crime” deserving harsh punishment. Given that protesters are often arrested on trumped-up charges of resisting or obstructing police, these laws can be a major part of a crackdown on dissent.

The materials from which the Trump forces are seeking to assemble an even more repressive state are readily to hand. It was under Obama and his predecessors that local police forces built up a colossal arsenal of military weaponry to repress a civilian population. It was under Obama that an unprecedented apparatus for mass deportations was constructed, which Trump simply has to tweak and speed up.

Vast and intimidating though it is, however, we should not overestimate the power of the repressive arm of the US state. Recent history in New York, where determined campaigning against “stop and frisk” policing has led to a major decline in the practice, has shown political mobilisations can win some limits on the use of police powers – especially in the big cities.

Police murder and mass repression could not stop the militant organising drives and strikes that transformed the US union movement in the 1930s. Mass jailings and assassinations could not prevent the civil rights movement of the 1950s and 1960s from winning significant gains. And the fatal shootings at Kent State (and at Jackson State College in Mississippi, just days later) could not save the US ruling class from humiliating defeat at the hands of a peasant army in Vietnam, as a mass anti-war movement encouraged open mutiny in the US armed forces.

These traditions – of courage, organisation and mass, militant defiance – should inform and inspire today’s movement of resistance to Trump and all he stands for.