One of the most tangible rallying cries in the wake of the massive protest over the death of George Floyd in America has been "defund the police".

It's been shouted, painted on placards and turned into hashtags for social media campaigns.

US President Donald Trump has vowed there won't be "a dismantling of police", but some cities have already taken the first steps to doing just that.

Here's what you need to know.

What does 'defund the police mean'? Why now?

"Defund the police" means taking funds allocated for police forces across the US and channelling them into other public programs.

Supporters argue that police in America have become a catch-all service responsible for dealing with all of society's problems, something they were never meant to do and are not trained to do.

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State and local governments in America spent $US115 billion ($164 billion) on policing in 2017, according to data compiled by the Urban Institute.

Supporters want those funds redirected into things like:

• Education
• Housing
• Mental health support
• Social services

"When we talk about defunding the police, what we're saying is 'invest in the resources that our communities need," Black Lives Matter co-founder Alicia Garza told NBC's Meet the Press.

The idea being that if you properly fund those programs, there won't be a need for police.

Activists say that previous solutions like body cameras and oversight boards have failed to reform police departments and that now is the time to look at systemic solutions to a problem with a long history.

Won't that mean there are zero police?

In most cases, no.

Supporters say the idea is designed to get society thinking about wholesale change to the concept of police as we know them.

"Are we willing to live in fear that our lives will be taken by police officers who are literally using their power in the wrong way?" Garza told Meet the Press.

There are some groups that support the total abolition of police. One of them is MPD150, a group "working towards a police-free Minneapolis".

"Crime isn't random. Most of the time, it happens when someone has been unable to meet their basic needs through other means," the group writes on its website.

"By shifting money away from the police and toward services that actually meet those needs, we'll be able to get to a place where people won't need to rob banks.

The "broken windows" theory of policing is a controversial approach that believes cracking down on minor crimes can prevent serious ones. Groups like Movement for Black Lives have pushed back against the theory, arguing it disproportionally targets communities of colour.

Have the protests made any cities jump on board with the idea?

Yes.

In Minneapolis, the city where George Floyd was killed, nine of the 12 City Council members pledged to dismantle the city's police department.

"It is clear that our system of policing is not keeping our communities safe," said Lisa Bender, the council president.

"Our efforts at incremental reform have failed, period."

In New York City, Mayor Bill de Blasio said that the city would move funding from the NYPD to youth initiatives and social services, while keeping the city safe. He's yet to give any details of how it might happen.

In Los Angeles, Mayor Eric Garcetti vowed to cut as much as $US150 million ($214 million) that was part of a planned increase in the police department’s budget. Last year, the Los Angeles Police Department had an annual budget of $US1.189 billion.

Has it been done before?

Yep, in a couple of places.

In Eugene, Oregon a program called CAHOOTS (Crisis Assistance Helping Out on the Streets) is now tackling up to 17 per cent of 911 calls that come into the Eugene Police Department.

When a 911 operator receives a mental-health-related call, a member of CAHOOTS is sent out instead of a police officer. CAHOOTS teams are made up of a medic and a crisis worker who are trained to de-escalate situations and help a person move on to the next step of treatment.

In 2012, with crime rampant in Camden, New Jersey, the city disbanded its police department and replaced it with a new force that covered Camden County.

What about those who oppose it?

US President Donald Trump is firmly against the idea of defunding police forces across America.

"We won't be defunding our police. We won't be dismantling our police. We won't be disbanding our police," Mr Trump said.

Mr Trump has little direct authority over most police in the US, with state and local governments controlling their own departments.

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His Democratic opponent at the November presidential election, former vice-president Joe Biden, is also against the idea of defunding police.

Representative Karen Bass, a Democrat from California and chairwoman of the Congressional Black Caucus, said part of the movement is really about how money is spent.

"Now, I don’t believe that you should disband police departments," she said in an interview with CNN.

"But I do think that, in cities, in states, we need to look at how we are spending the resources and invest more in our communities."

David Kennedy, director of the National Network for Safe Communities at John Jay College for Criminal Justice in New York, told Axios that there isn't evidence to prove that defunding police will work because it hasn't been widely tried yet.

The Los Angeles Police Protective League, the union for the city's rank-and-file officers, said budget cuts would be the "quickest way to make our neighbourhoods more dangerous."

ABC/AP