Trump said the shooter, identified by authorities
as Stephen Paddock, was a "sick man, demented man," but did not answer reporters' questions at the White House about whether he committed an act of domestic terror. On Monday, White House press secretary Sarah Sanders said it was "premature" to judge that question, pointing to the ongoing investigation.
Law enforcement authorities similarly declined to use the term.
"We have to establish what his motivation was first," said Clark County Sheriff Joseph Lombardo. Yet others, such as a former astronaut and gun-control advocate Mark Kelly, were unequivocal.
"This was an ambush if there ever was one," said Kelly. "This was domestic terrorism."
But here's the problem: There is no such charge under federal law.
The confusion appears to stem, at least partly, from the fact that the US code does include a statutory definition of "domestic terrorism" -- as acts "dangerous to human life and appear to be intended to intimidate or coerce a civilian population" or to influence government policy or conduct -- but it is not a standalone criminal charge.
"There is not a domestic terrorism crime as such," FBI Director Christopher Wray
said in a Senate hearing just last week. "We in the FBI refer to domestic terrorism as a category but it's more of a way in which we allocate which agents, which squad is going to work on it."
CNN Legal Analyst Page Pate says that Congress bears some of the responsibility for the colloquial use of the term.
"The problem is that Congress defined domestic terrorism in the criminal code, but there are no criminal penalties," Pate said in an interview with CNN Monday.
The practical effect in many cases results in assailants instead being charged with other crimes, such as using a weapon of mass destruction in the case of 1995 Oklahoma City bomber Timothy McVeigh.
But the lack of a formal charge of domestic terrorism hasn't stopped some lawmakers, legal experts and others from questioning whether labels still matter.
Republican Sen. Ron Johnson, chairman of the Senate homeland security committee, asked Wray last week if the FBI takes the threat of ISIS-related terrorism cases "any less seriously" than those committed by white supremacists or if he's noticed any difference in charging decisions.
"No, we do not," Wray said. "There may be reasons why it's simpler, easier, quicker, less resource-intensive and you can still get a long sentence with some of the other offenses. ... And so, even though you may not see them, from your end, as a domestic terrorism charge, they are very much domestic terrorism cases that are just being brought under other criminal offenses."