President Donald Trump has said major US cities are seeing a spike in crime, and has offered to send in federal law enforcement to tackle the situation.
He has denounced a string of Democrat-run cities which are "plagued by violent crime".
New York, Chicago, Philadelphia, Detroit, Baltimore and all of these - Oakland is a mess. We’re not going to let this happen in our country.
We've looked at violent crime, and found it's down overall in many cities, but murders and shootings have risen sharply in some.
Violent crime continues to fall
President Trump has said the crime rate in certain cities such as New York is "through the roof".
But in many major US cities, including Chicago and New York, violent crime overall is down compared with the same time last year.
Various cities define violent crime in slightly different ways, but it usually includes murder, robbery, assault and rape.
Individual years can fluctuate but violent crime across America has been on a downward trend since the 1990s.
In April and May, violent crime in many US cities declined significantly compared with previous years, due in part to coronavirus lockdown measures.
But President Trump has pointed to a string of murders in certain cities, and homicides in contrast have increased sharply in some areas.
Where have murders risen?
A review of data from 27 major American cities found that Chicago led the way as homicides surged.
The president has sent more than 100 federal agents to help local law enforcement in Chicago.
As of 23 August, murders were up more than 50% on this time last year.
President Trump has also pointed to a string of shootings in recent months, and shooting incidents in Chicago are up by more than 60% compared to the same point last year.
It's a similar story in New York - shootings have almost doubled compared to the same point in 2019, and the murder rate is up by more than a third - although assaults, rapes and robberies are down.
New York's murder rate has decreased significantly since the 1990s, but June saw the most shootings in a single month since 1996, according to the New York Police Department.
President Trump has proposed expanding the deployment of federal law enforcement, as has been the case in Chicago, to New York as well as the north-eastern city of Philadelphia.
Philadelphia is seeing a spike in murders, while reports of other violent crimes have declined.
Murders are down elsewhere
Albuquerque, New Mexico, is another city President Trump has sent dozens of federal agents into, but murders have fallen compared with previous years.
The police chief in the city has said: "Contrary to claims by politicians in Washington DC, Albuquerque has been keeping overall violent crime flat and has reduced homicides thus far this year."
Murders in Albuquerque, a city of more than half a million people, have dropped to 38 according to the latest data available, compared with 44 at the same point in the previous two years.
Other cities earmarked by President Trump have also seen mixed trends. Murders are down in Baltimore, but up in Oakland and Detroit compared with the same time last year.
Why are some cities seeing a spike in murders?
It's hard to put it down to one reason.
Crime often rises in the summer due to a combination of reasons, such as no school and more outdoor activity.
Richard Rosenfield, an American criminologist, says: "Typically as weather warms up, we see an increase in street crime, including homicides."
This summer has also seen people re-emerging from lockdowns in various states.
The mayor of Chicago has put the rise in murders down in part to a "perfect storm" created by coronavirus, and the mayor of New York says the spike has been fuelled by "horrible dislocation" caused by the pandemic.
The ongoing pandemic has had widespread implications, including for law enforcement.
Many courts in the US have been closed, and some offenders have been released to stop the spread of coronavirus. That has led "to a feeling among offenders that they can commit crimes with impunity", according to a report by the Police Executive Research Forum.