After a driver plowed a rented truck into bikers and pedestrians on Manhattan's west side on Oct. 31 and went on to shout "Allahu akbar," or "God is great" in Arabic, investigators quickly took to calling the incident terrorism.
The attack left eight dead and 11 wounded, according to reports.
The reason comes down to an attacker's motivation. Authorities have yet to name a motive for the Las Vegas attack, but officials quickly began identifying clues on Oct. 31 after what would be the deadliest terrorist attack in New York since Sept. 11, 2001.
NYPD Commissioner James O'Neill recieves a brief with FBI NY, NYPD Counterterrorism, Mayor de Blasio, and others after a motorist killed 8 and wounded others in an apparent terrorist attack in NYC on Oct. 31, 2017. (image @NYPDONeill Twitter)
"This was an act of terror, and a particularly cowardly act of terror aimed at innocent civilians, aimed at people going about their lives who had no idea what was about to hit them," Mayor Bill de Blasio of New York said at a news conference just two hours after the truck attack.
"He did make a statement when he exited the vehicle," New York Police Commissioner James O'Neill said of the truck's driver, identified by authorities as Sayfullo Habibullaevic Saipov, a 29-year-old Uzbek national who had lived in Tampa, Florida. The attack ended when Saipov was shot by the police; he was then hospitalized.
"And if you just look at the M.O. of the attack, that's consistent with what's been going on," O'Neill added. "So, that, along with the statement, that's enabled us to label this a terrorist event."
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Multiple news outlets reported that investigators found a note in Saipov's car pledging allegiance to ISIS, though the terrorist group's news agency Amaq made no mention of the attack immediately afterward.
New York's governor, Andrew Cuomo, called the Oct. 31 carnage a "lone wolf" attack and said there was no evidence to suggest it was part of a wider plot.
So even though authorities think Saipov acted alone, the attack is still being investigated as terrorism because of his apparent political motivation.
NYPD Commissioner James O'Neill at 1PP in a press conference regarding the terrorist attack that killed 8 in NYC on October 31, 2017. (image @NYPDSpeechley Twitter)
"While definitions for terrorism differ, the overwhelming majority of them distinguish terrorism from other crimes of violence by the purpose of the actor, not the severity of the harm caused," Robert Eatinger, the former senior deputy general counsel at the CIA, told The Cipher Brief in October.
In response to the attack, President Donald Trump tweeted that he had "ordered Homeland Security to step up our already Extreme Vetting Program."
Saipov, however, hails from Uzbekistan, a country never listed in Trump's proposed travel bans. Saipov used no firearms that legislation could restrict access to. And some of those who knew Saipov, who spent the months before the attack driving for Uber in New Jersey, have said he did not display any warning signs.