President Donald Trump tweeted Friday that his administration will ban bump stocks devices that "turn legal weapons into illegal machines" and blamed former President Barack Obama for allowing them in the first place.His tweeted comments come a day before student and teen-led nationwide marches calling for gun policy reform.Attorney General Jeff Sessions in a statement on Friday announced the Department of Justice has begun the process to amend federal firearms regulations to clarify that bump stocks should fall under the technical definition of "machinegun" under federal law. ""Legislation is the only answer," she said.The actions taken Friday by the Justice Department effectively open a rule change for public debate.Following the school shooting at Marjory Stoneman Douglas High School in Florida last month, National Rifle Association spokesman Dana Loesch told ABC's This Week that the organization doesn't support a bump stock ban. A bump stock is an attachment that allows a semi-automatic rifle to achieve a fully automatic weapon’s “cyclic firing rate to mimic nearly continuous automatic fire,” according to the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). But Sessions’ statement on Friday said that bump stocks “allow a shooter of a semiautomatic firearm to initiate a continuous firing cycle with a single pull of the trigger.”

The Trump administration has been reviewing the legality of bump stocks since December 2017. BAD IDEA. More: 'Bump stocks' may be new to you, but federal officials have grappled with them for years

In 2010 the Bureau of Alcohol, Tobacco, Firearms and Explosives determined that because bump stocks don't have any moving parts, they are a "firearm part" could not be regulated as a firearm under existing gun laws.
The US Department of Justice announces it will reclassify bump stocks as machine guns, effectively outlawing them.