(CBS) – Illegal guns and repeat gun offenders are the top priority for a task force that is combining Chicago police, ATF agents and prosecutors at the state and federal level.

Friday morning, President Donald Trump tweeted that “crimes and killings in Chicago have reached such epidemic proportions that I am sending in federal help.”

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Now we know part of that help is an additional 20 ATF agents assigned to the Chicago Gun Strike Force.

Members will work with the Chicago Police Department’s Organized Crime Bureau to combat gun violence in the city.

“This task force is going to have really two missions. The first is going to be to identify illegal traffickers, and the second is going to be to work on some of these open shootings,” Anthony Riccio, chief of that bureau, said.

To that end, a special ATF van has already been used to compare shell casings to the National Integrated Ballistic Information Network.

It’s already been used 96 times in about two weeks.

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“The process of taking that gun, test-firing it, comparing the shell casings and getting information on other shootings that gun was involved in, that will take hours,” Riccio said.

CPD officials hope that will lead to more arrests, and once arrested, repeat gun offenders will face tougher penalties on both the state and federal level.

The former police superintendent, Garry McCarthy, is doubtful the new task force will make a difference.

“This is not a new concept. We had an enhanced deployment from the ATF under my watch,” he tells CBS 2’s Mai Martinez.

“We’re not going to reduce gun crime in Chicago until we change the political environment that is anti-police, which, as you’ve heard me say before, is emboldening criminals and hamstringing the police.”

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The feds say they’re also stepping up prosecution of gun cases. So far this year, they’ve prosecuted more than all of last year combined.