Washington (CNN) President Donald Trump said on Tuesday that he has directed his attorney general to propose changes that would ban bump fire stocks, which make it easier to fire rounds more quickly. The move adds his voice to a process that began in December, two months after a gunman used the device in a shooting that left scores dead at a concert in Las Vegas.

"Just a few moments ago I signed a memo directing the attorney general to propose regulations that ban all devices that turn legal weapons into machine guns," Trump said at a Medal of Valor event at the White House, addressing Attorney General Jeff Sessions.

"I expect these regulations to be finalized, Jeff, very soon," Trump said.

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While the President's comment on the issue is new, the Justice Department had announced in December, in the wake of the Las Vegas shooting, that it had begun the rule-making process that could allow it to reinterpret the legality of the devices.

That process is ongoing. The proposal submitted by the Bureau of Alcohol, Tobacco, Firearms and Explosives, which questioned the statutory definition of a machine gun under federal gun laws, drew more than 35,000 comments from the public, far more than usual, which likely signals that pro- or anti-gun control groups -- or both -- mobilized their membership and email lists to weigh in. Comments were due by January 25.

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