Sayfullo Saipov – whose first name translates "Sword of Allah" – managed to slip through the cracks of several law-enforcement systems designed to prevent terrorism.

Similar to previous "lone wolf" terrorists in recent years, he had been interviewed by the FBI on suspicion of a connection to terrorism. Second, the mosque he attended in Paterson, New Jersey, had been under the scrutiny of a New York Police Department unit that was shut down three years ago under pressure from Islamic activists. Third, the NYPD had a program in place to help area businesses that rent trucks – such as the Home Depot where Saipov obtained his weapon – spot potential threats. And fourth, through the State Department's Diversity Visa Program – a lottery for people from countries with few immigrants in the United States – he immigrated to the U.S. in 2010 from Muslim-majority Uzbekistan, which has spawned thousands of jihadists now fighting worldwide.

The flaw in each of those systems is the unwillingness to make adherence to the teachings of Islam part of the criteria law-enforcement personnel use to judge whether or not a person should be regarded as a threat, according to former law enforcement officials.

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"Without Islam there is no Islamic terrorism," said Bruce Tefft, a former counter-terrorism adviser to the NYPD and a founder of the CIA’s Counter-Terrorism Unit.

If perpetrators such as Saipov "say they are motivated by Islam, then it's Islamic terrorism," he said.

"The idea that we as Westerners can define Islam for Muslims is ludicrous," said Tefft, who spent 17 of his 21 years in CIA clandestine services stationed overseas, including hot spots such as Mogadishu and Angola.

Wednesday afternoon, prosecutors said that, inspired by ISIS videos, the 29-year-old Saipov began planning the attack about a year ago while in the United States. Investigators said he chose Halloween because he believed there would be more people on the street, and his truck attack followed instructions ISIS posted online "to a T."

Since 2014, there have been 15 vehicular attacks in the West by jihadist terrorists, killing 142 people, according to the nonpartisan research institution New American.

Saipov had been interviewed in 2015 by federal agents in the Department of Homeland Security Investigations Unit about possible ties to suspected terrorists, but the agents didn't have enough evidence to open a case on him, according to law enforcement officials who spoke to ABC News.

The prior contact by law-enforcement with a perpetrator of a terrorist attack is a familiar pattern, as WND has reported. Khalid Masood, for example, the 52-year-old Muslim who ran over pedestrians on Westminster Bridge then killed a police officer at the Parliament building in March had been investigated for concerns about “violent extremism.” And at one point or another prior to their attacks, law enforcement also had an eye on San Bernardino killer Syed Farook, Fort Hood killer Nidal Hasan, Boston Marathon murders Tamerlan and Dzhokhar Tsarnaev, Chattanooga killer Muhammad Youssef Abdulazeez and Orlando killer Omar Mateen.

After the London attack, Philip Haney, a former Islam subject matter expert for U.S. Customs and Border Protection, asked: "What is the law-enforcement standard that Masood didn't meet that caused his case to go dark?"

He points out that law-enforcement investigators continue to be hindered from probing the religious motivation of individuals such as Masood to determine whether or not they pose a threat to national security.

"The incessant refusal to plainly and courageously identify the malevolent ideology inherent in Islamic supremacism" is putting the nation at risk, Haney said at the time.

A federal official told ABC that Saipov's name and address was listed as a "point of contact" for two different men whose names were entered into the Counterterrorism and Criminal Exploitation Unit’s list after they came to the United States from "threat countries."

One of the two men disappeared and is being sought by federal agents as a "suspected terrorist."

After arriving in the U.S. in 2010, Saipov lived in Ohio, Florida and Paterson, N.J., where federal agents interviewed him in 2015.

In a White House Cabinet meeting Wednesday, President Trump vowed to eliminate the Diversity Visa Lottery that brought Saipov to the U.S.

"I am, today, starting the process of terminating the diversity lottery program," Trump said. "I am going to ask Congress to immediately initiate work to get rid of this program, diversity lottery, diversity lottery. Sounds nice, it is not nice, it is not good. It hasn't been good and we have been against it."

He said the administration is "going to quickly as possible get rid of chain migration and move to a merit-based system."

'Psychological warfare'

Under Police Commissioner William Bratton, the NYPD disbanded its Demographics Unit in 2014 – which included plainclothes detectives who monitored Muslims and mosques – in response to pressure from Muslim activists who charged it was discriminatory and motivated by an animus toward Muslims.

Activist Linda Sarsour of the Arab American Association of New York, who was featured at the Women's March in Washington after Trump's inauguration, charged the unit "created psychological warfare in our community."

One of the targets of the unit's surveillance was the Omar Mosque near Saipov's home in Paterson, N.J., which investigators said was a source of "budding terrorist conspiracies."

While the surveillance unit no longer exists, NYPD has a program called SHIELD that coordinates with vehicle rental businesses to spot possible terror threats.

"We did extensive outreach to the truck rental business. We visited over 148 truck rental locations in this area,” John Miller, NYPD deputy commissioner of intelligence and counterterrorism, explained to reporters Tuesday. "The industry has had a high level of awareness on this matter from the NYPD."

Tefft recalled to WND that shortly after 9/11, when he was a counter-terrorism adviser to the NYPD, the department responded to intelligence of possible attacks on New York City being carried out using Zodiac inflatable boats.

NYPD contacted outlets for the boats, instructing employees to look out for atypical renters or buyers, such as people who don't demonstrate knowledge of how to operate the boat or who want to hire or buy a large number of them.

"It was pretty simple, and they got a lot of callbacks, but not one of them panned out," said Tefft.

Asked whether or not NYPD's criteria for determining a threat included any religion-related indicators, he replied: "Oh no, not at all."

NYPD did not reply to WND's questions about its SHIELD program, including what criteria rental agencies should use to determine who poses a threat.

On a dedicated Web page, the NYPD says the concept of its SHIELD system is that "with training, the private sector is best situated to notice something that may be out of place or amiss and then alert the NYPD."

The NYPD says it works with truck rental firms and others "with training and regular interaction specific information is transmitted directly by: In-person intelligence and threat briefings conducted by Counterterrorism Bureau and Intelligence Division personnel, Informal conferrals with Patrol Borough Counterterrorism Coordinators and NYPD Website postings."

Through the SHIELD program, the New York Post reported, law-enforcement agents have talked to some 20,000 people in the private rental business in New York City and nearby towns over the past two years, since ISIS urged urged attacks with motor vehicles.

But a law-enforcement official who spoke to the Post said Saipov wouldn't have raised any red flags, because he had previously worked as a commercial truck driver and had a license in good standing.

"You're asking private commercial companies to do our job … to lose cash revenue ... or you’re asking them to profile certain types of people, which they absolutely are not going to do," the source said.

Islam expert Robert Spencer said Tuesday on his Jihad Watch site that the unwillingness to "profile" is at the heart of the problem.

"Does he look like he could be a jihad terrorist? Certainly," Spencer wrote. "But to acknowledge that would be to engage in racial profiling, and given the decidedly Islamic style of his facial hair (a hadith depicts Muhammad telling Muslims to trim their mustaches but not their beards, because the Jews and Christians trim their beards but not their mustaches), religious profiling, a manifestation of 'Islamophobia,' as well."

Spencer said one could imagine what would happen if a Muslim was denied a rental: "tomorrow the Council on American-Islamic Relations would be there, complaining about Islamophobia in Home Depot. Your face would be on NY1, CNN, MSNBC. You might even make the front page of the New York Times: 'Home Depot Clerk Denies Service to Man Because He Was Muslim.'"

Uzbek terrorists

The Wall Street Journal pointed to a 2015 report by the International Crisis Group warning that growing numbers of Central Asians were traveling to the Middle East to support or fight for ISIS, with Uzbeks being the most numerous among them.

With ISIS fighters beginning to leave Syria and Iraq, Uzbek nationals pose an added risk in many parts of the world, the Wall Street Journal said, noting they have been linked to a handful of terrorist cases in recent years, including incidents in Sweden and Russia.

In the U.S., a number of Uzbeks were charged in 2015 for conspiring to join or aid ISIS. The Journal said the arrests were the result of an investigation that began after one of them posted to an Uzbek-language website that called for visitors to join ISIS.

In April, a 39-year-old Uzbek national drove a truck into a crowd in the Swedish capital of Stockholm. He was known to the police for failing to report for his deportation. The Uzbek government linked him to ISIS.

The same month, Russian authorities identified an ethnic Uzbek citizen of Russia as the perpetrator of a bombing on the St. Petersburg metro that killed at least 14 people. In January, an Uzbek national opened fire on Istanbul’s Reina nightclub, killing at least 39 people. ISIS claimed responsibility for the attack.

Central Asians from Uzbekistan and Kyrgyzstan were among the assailants in the June 2016 attack on Istanbul’s airport in which more than 40 people were killed.

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