(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.
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.
If after reviewing the comments the ATF decides to rewrite the machine gun definition to include bump stock devices, barring their sale and possession, the agency could then re-examine prior rulings and guidance it had made on the production of the device to private manufacturers.
In a statement Tuesday, Justice Department spokeswoman Sarah Isgur Flores said: "The Department understands this is a priority for the President and has acted quickly to move through the rulemaking process. We look forward to the results of that process as soon as it is duly completed."
Earlier Tuesday, White House press secretary Sarah Sanders said Trump had ordered the Justice Department and the ATF to review bump fire stocks, which she said had been completed. She said movement on that front would take place shortly.
"The President, when it comes to that, is committed to ensuring that those devices are -- again, I'm not going to get ahead of the announcement, but I can tell you that the President doesn't support use of those accessories," Sanders said.
Sen. Dianne Feinstein, a California Democrat who submitted a bill last year in the Senate that would ban bump stocks, welcomed Trump's support for a ban but cautioned that new agency rules could fail because of the ATF's past stance on the devices.
"If ATF tries to ban these devices after admitting repeatedly that it lacks the authority to do so, that process could be tied up in court for years, and that would mean bump stocks would continue to be sold," Feinstein said.
"Legislation is the only answer," she said. "Words are one thing, Mr. President, but we need meaningful action."
Asked on Tuesday whether the President would support steps to raise the federal minimum age for buying military-style weapons, such as the AR-15, Sanders did not rule it out.
"I think that's certainly something that's on the table for us to discuss and that we expect to come up over the next couple of weeks," Sanders said.
In most states, the minimum age for purchasing the AR-15 is 18, while some states set the minimum age for handguns at 21.