What makes the Halloween truck attack on New York's West Side Highway terrorism

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Sayfullo Habibullaevic Saipov.

• 29-year old Sayfullo Habibullaevic Saipov is suspected to have rammed a car down a Manhattan bike path, killing 8 and injuring 11.
• Saipov reportedly had a note in his car pledging allegiance to ISIS.
• Saipov's apparent political motivation caused the attack to be investigated as an act of terror.

After a rented truck ploughed into bikers and pedestrians on Manhattan's west side, and the driver shouted "Allahu Ackbar," or "God is great" in Arabic, investigators quickly took to calling the incident terror.

The attack left eight dead and 11 wounded, according to reports.

But just a month earlier, when Stephen Paddock opened fire from a high floor in the Mandalay Bay Casino and Resort in Las Vegas, leaving 58 dead and 500 injured, police did not investigate the incident as terror.

The reason why comes down to motivation.

"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," said New York City Mayor Bill de Blasio just hours after the attack.

"He did make a statement when he exited the vehicle," New York Police Department commissioner James O'Neill said of the suspect, 29-year-old Sayfullo Habibullaevic Saipov, an Uzbek national from Tampa, Florida.

"And if you just look at the M-O of the attack - that's consistent with what's been going on. So, that, along with the statement that's enabled us to label this a terrorist event," O'Neill added.

Multiple outlets reported that investigators found a note in Saipov's car pledging allegiance to ISIS, though the terror group's news agency Amaq made no mention of his attack immediately after.

But New York Gov. Andrew Cuomo called Tuesday's carnage a "lone wolf" attack and said there was no evidence to suggest it was part of a wider plot.

So even though Saipov likely acted alone, he is still being investigated as a terrorist due to his political motivation.

"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," said Robert Eatinger, the former Senior Deputy General Counsel at the CIA told the Cipher Brief in October.

Bebeto Matthews/AP

A New York Police Department officer stands next to a body covered under a white sheet near a mangled bike along a bike path Tuesday Oct. 31, 2017, in New York.

In response to the apparent terror attack, President Donald Trump tweeted that he had "ordered Homeland Security to step up our already Extreme Vetting Program," and taking the opportunity to criticize political correctness.

But Saipov hails from Uzbekistan, a country never listed in Trump's proposed travel bans. Saipov used no firearms that legislation could restrict access to. According to those who knew Saipov, he didn't display any warning signs.

Saipov spent the months before the attack driving for Uber in New Jersey. It's still unclear what led him to commit the apparent act of terror or promote the cause of ISIS in the single bloodiest attack in New York City since September 11, 2001.