The president told reporters Monday that an unnamed "top general" lamented the state of U.S. military supplies when he took office.
Twenty one Attorneys General asked Congress to expand background checks to include ammunition purchases.
Tendai Muswere, 26, claimed he was planning to use the weapons as props in a sci-fi film he was preparing to shoot.
"Of all the gun tragedies, this hit the closest to home for a lot of us. I felt like I had to do something or else I would really be complicit in a company that was continuing to sell firearms."
"While these types of firearms are legal and easily obtainable in other countries, they are illegal here in Scotland and across the U.K. Buying them can land you in jail," a top law enforcement chief said.
Maximilien R. Reynolds reportedly possessed an unassembled AR-15-style rifle, combat equipment and 300 rounds of ammunition.
Haig said that he no longer sells ammunition and that he doesn't know "wacko" Stephen Paddock.
California will be the first state to completely ban hunting with lead bullets after decades of arguments between hunters, environmentalists and regulators.
It is impossible to make America first by treating the world last.
The court found that military-style assault weapons and large-capacity magazines are not protected under the Second Amendment's right to bear arms.
The move came weeks after Moscow raised the stakes with its intervention in the long-running civil war.
Britain intends to bolster its defenses against the threat of an Argentine invasion.