This is surprising, although the intent is unclear thus far:
What we can say definitively from this news is that Trump is rattled by the groundswell of rage following the Parkland shootings, spearheaded by the students of Marjory Stoneman Douglas High. He was pushed into action, but whether this action is a legitimate attempt to stop violence, or a move designed to placate the opposition without enacting any real change…well, that remains to be seen.
Thus far, that short report is all that’s available on sites like WaPo, which replicates the AP tweet with the same text. A “bump stock” is an addition to semi-automatic weaponry that enables them to fire up to 800 rounds per minute, thus mimicking an automatic weapon. The shooter in Florida, Nikolas Cruz, was apparently not using a bump stock, though Stephen Paddock, the Las Vegas shooter, was.
At the moment, it seems like something less than a half-measure—the NRA actually supports banning bump stocks, but the ban, while positive, won’t have the impact that an assault weapon ban or other strict gun control legislation might have. Crucially, it will also not significantly cut into the profits of the gun industry.
Finally, without congressional legislation, this is more of a suggestion than a concrete ban, as his quote at a White House event today made clear:
“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.