WASHINGTON (Reuters) - Violent crime in the United States increased in 2015 but remained far below peak levels of the 1990s, the Federal Bureau of Investigation said on Monday as presidential candidates Hillary Clinton and Donald Trump prepared for a debate that is likely to focus on public safety. 
 
 Phone banks dedicated to the Federal Bureau of Investigation are shown during a tour of the Multi-Agency Communications Center (MACC) at an undisclosed location in the Chicago suburbs May 17, 2012. REUTERS/Frank Polich 
 
 While murder, rape and assault remained far below the peak levels of the 1990s, last year’s increase in the violent crime rate could provide fodder for Trump, a Republican who has portrayed himself as a “law and order” candidate willing to support aggressive policing tactics. Clinton, a Democrat, has said many of his crime-fighting proposals amount to unconstitutional attacks on American freedoms. 
 
 The FBI report could “be turned into political football,” said Harvard Law School research fellow Robert Smith. 
 
 At 372.6 incidents per 100,000 people, the 2015 violent-crime rate is higher than the 2014 rate of 361.6 but still well below the 1996 level of 636.6. The increase was most pronounced in big cities, the report found. 
 
 On the campaign trail, Trump frequently points to rising crime rates as a reason to support “stop-and-frisk” tactics and other police methods that critics say unfairly target minorities. 
 
 Clinton has pushed for stricter gun control to help curb violence and has called for national guidelines on the use of force by police officers. 
 
 In 2015, there were an estimated 15,696 murders in the United States, compared with an estimated 14,164 the prior year, according to the report. Last year’s crime rate was still lower than in 2012 and earlier years, the FBI found. 
 
 Crime was highest in the southern United States, the report found. At 45.9 per 100,000 people, the murder and manslaughter rate in the region was more than twice as high as in the West, the Midwest and the Northeast, according to the FBI. Rates of rape, assault and property crime were dramatically higher as well. 
 
 FBI Director James Comey warned last year that violent crime in the United States might rise because increased scrutiny of policing tactics had created a “chill wind” that discouraged officers from using aggressive tactics. 
 
 The rise in crime has been concentrated in big cities’ segregated and impoverished neighborhoods. Experts said crime there can best be fought through better community policing and alternatives to incarceration for nonviolent crime. 
 
 “We’re just beginning to see a shift in mentality in law enforcement from a warrior mentality... to a guardian mentality,” Carter Stewart, a former prosecutor for the Southern District of Ohio, said on the teleconference. “I don’t want us as a country to go backwards.” 
 
 In Chicago, 54 more people were murdered in 2015 than in the previous year, a 13 percent jump in the city’s murder rate, according to an April study by New York University’s Brennan Center for Justice. ||||| Violent crime rates in the U.S. are reaching historic lows, according to new FBI data released Monday. 
 
 Instances of murder declined overall by 1.9 percent from 2010 figures, while rape, robbery and aggravated assault declined by 4 percent nationwide, according to records from more than 14,000 law-enforcement agencies around the country, FBI spokesman Bill Carter told msnbc.com. 
 
 The number of property crimes also registered a 0.8-percent drop, motor-vehicle thefts declined by 3.3 percent, and arson was down by 5 percent. 
 
 Although the findings, released in the FBI’s Preliminary Annual Uniform Crime Report, represent a seemingly small decline in crime overall, they aren’t just a blip. Rather, criminologists say, the decline is part of larger downward trend and the result of a series of changes that have contributed to a more peaceful society. 
 
 “This is actually a pretty significant drop, which is fascinating because we’d normally expect crime to go up when we’re in an economic downturn,” Gary LaFree, a criminology professor at the University of Maryland, told msnbc.com, adding that the U.S. is experiencing the lowest crime levels since World War II. 
 
 According to FBI analysis, the homicide drop would mean that nearly 280 fewer Americans were murdered last year, which would be the lowest homicide death toll since the mid-1950s. 
 
 LaFree said a combination of factors – from a weak economy and an aging population to increased immigration and a more robust police presence across the country – have contributed to the drop. 
 
 “One of the responses of society is to pull together when there’s a huge crisis and a feeling of great difficulty,” LaFree said, adding that the economic climate may have contributed to this peaceful trend. 
 
 Additionally, with the current U.S. median age at 37.2 years, older than ever before, the aging population is another possible cause, LaFree said. “There is some truth to the fact that younger people commit more crimes,” he said. 
 
 “We also have a record number of immigrants, and contrary to popular belief,” LaFree said, “immigrants have lower crime rates than the rest of society.” 
 
 But some argue the data may not signify such remarkable changes. 
 
 “Year-to-year changes are notoriously volatile, especially for lesser-volume crimes like murder,” James Alan Fox, a criminologist at Northeastern University in Boston, wrote in his blog. “They must be viewed with caution, avoiding the temptation to make too much out of rather little.” 
 
 Fox said it’s possible the long-term downturn in crime has slowed and even bottomed out. 
 
 Still, LaFree argued there’s a reason the numbers indicate what they do. 
 
 “Compared to years ago, “There’s nothing that’s ripping apart the fabric of society in a political sense,” LaFree said. 
 
 The mass protests during the Vietnam War and the beginnings of crack cocaine epidemic contributed to more violent crimes in the past, LaFree said. He said he thinks there are fewer problems as extreme as either of those in society today. 
 
 As for the serious crimes that do occur, there exists a strong deterrence factor in the prison system, despite debates about its effectiveness, he said. 
 
 But more importantly, LaFree said, there has been a “quiet revolution” in law-enforcement policy over the past few years. 
 
 “Police departments have become much more proactive across the country,” Lafree said. “They used to deploy resources to handle crime, but now they’re much more likely to target problems beforehand and emphasize a solution.” 
 
 Fox, however, warned against resting on news that could be seen as too positive. 
 
 “With rates relatively low, this is not the time to diminish crime fighting-efforts,” he said. “If we naively presume that the crime problem has been solved (as opposed to just controlled for the time being), the crime rate could easily rebound.” 
 
 The FBI's final crime figures will be released this fall. 
 
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– The number of murders in the US rose 11% last year from 2014, while the number of violent crimes saw a modest increase of 4% after two years of decline, per an FBI press release. Rapes rose 6.3%, aggravated assaults increased 4.6%, and robberies rose by 1.4% during the same period. These stats come from the FBI's latest crime report, though NPR notes it's important to put the figures in context: These violent crimes were still way down compared to other recent years, and especially more than 20 years ago, when figures spiked. For instance, despite its 11% increase this year, the number of murders dropped 9.3% from 2006. "The number of rapes is less than in 2009, the number of robberies less than in … 2013, and assaults less than in 2010. Still quite safe," a Fordham law professor and crime expert notes on Twitter. Not that it's all smooth sailing. US Attorney General Loretta Lynch addressed the increase Monday, noting that violence "tears at the fabric of our common life" and that "we still have so much work to do," per the Washington Post. And FBI Director James Comey said in May it doesn't make him feel better that violent crime has risen over the past year, even if it hasn't reached historic low points. In terms of last year's murders, firearms were involved in about 72% of the cases, and seven cities or regions—Chicago, Baltimore, Houston, Milwaukee, Philadelphia, Kansas City, and DC—accounted for much of 2015's spurt. Don't be surprised if the crime report comes up in Monday night's debate between Clinton and Trump: A Harvard Law School research fellow said Friday the stats could be turned into a "political football" during their faceoff, per Reuters. (Our most violent states.)