U.S. President-elect Donald Trump said in a Twitter message Monday that Chicago's mayor must ask for U.S. government help if the city fails to reduce its homicide rate, which hit a 20-year high last year.

The city responded that Trump and Mayor Rahm Emanuel had previously spoken and agreed to ways the federal government could help.

"Chicago murder rate is record setting — 4,331 shooting victims with 762 murders in 2016. If Mayor can't do it he must ask for Federal help!" Trump tweeted.