A leading US political commentator has said a travel ban or increased vetting would not have stopped the suspect in the New York City attack.
At least 11 people were injured and eight killed after a truck was driven into pedestrians on West Street in lower Manhattan.
The suspect has been named as 29-year-old Sayfullo Saipov, who had legally emigrated to the United States in 2010.
Saipov was reportedly shot by police in New York and was taken to hospital for treatment, and in the wake of the incident, US President Donald Trump called for Homeland Security to increase its vetting process.
Kate Andrews, who works at the Institute of Economic Affairs, pointed out other measures promoted by Trump - like increased background checks and the travel ban - to protect the US from terror would not have prevented the crime.
She told Julia Hartley-Brewer: "This man was from Uzbekistan; he had been in the country for seven years, he’d been traveling through several states.
"He was working for Uber but he’d passed the background check. This was not someone suspected – from the evidence so far – of planning an organised attack.
"ISIS has become very good at encouraging others to go out and replicate their kind of terror on their own. It’s much harder to spot and stop.
"For Trump to say this can’t be tolerated is correct, but the travel ban won’t stop this.
"Looking at background records, increasing background checks would not have stopped this."