The new rule, published by the Justice Department, requires manufacturers of 80% lower kits to include serial numbers. Gun shops will be forced to conduct background checks for anyone wanting to purchase these kits.

"It's going to help save lives, reduce crime and get more criminals off the streets," Biden said. "If you commit a crime with a ghost gun, expect federal prosecution."

The president picked up an 80% lower of a pistol and said: "This is the gun … It's not hard to put together … Doesn't take very long. Anyone could order it."

Biden also asked Congress to do more to combat gun violence, including passing universal background checks, banning assault weapons, and high-capacity magazines.

Also, Steve Dettelbach was introduced as the new nominee for the ATF head.

Update (1503ET): President Biden announces Steve Dettelbach, a former federal attorney for the Northern District of Ohio, as the next nominee to head ATF.

Update (1452ET): President Biden said it would be illegal for non-licensed gun manufacturers to make 80% lower kits. He also said gun shops would need to require background checks for anyone wanting to purchase these kits. Each kit will need to include a serial number (like a regular gun).