Saipov, 29, was charged with providing material support to the Islamic State (ISIS) militant group and violence and destruction of motor vehicles.
Eight people were killed and 11 others injured as his truck carved a path of destruction through several blocks of Lower Manhattan yesterday. Saipov crashed the truck into a school bus, left the vehicle brandishing imitation firearms. He was shot by police. It was the the worst terrorist attack in on the city since 9/11.
He appeared in federal court today in a wheelchair and did not enter a plea.
A 10-page complaint was filed by the FBI before a federal court in New York against him.
More From This Section
The FBI said that Saipov, a resident of New Jersey, was inspired by the ISIS to carry out the terrorist attack.
He "requested to display ISISs flag" in his hospital room and stated that he felt good about what he had done, the complaint said.
Saipov told investigators he was inspired by Islamic State videos, in particular one showing ISIS leader Abu Bakr al-Baghdadi, it said.
He began planning an attack a year ago and decided two months ago to use a truck, officials said.
"In particular, Saipov was motivated to commit the attack after viewing a video in which Abu Bakr al-Baghdadi... questioned what Muslims in the United States and elsewhere were doing to respond to the killing of Muslims in Iraq," the complaint said.
The cell phone also contained approximately 3,800 images, many of which appear to be ISIS propaganda.
Internet search history of the second cell phone reflects, among other things, that Saipov searched for a store in Passaic in New jersey on October 4, searched for Halloween in New York on October 15, and searched for truck rentals on October 18, the complaint said.
After Saipov rented the truck from Home Depot, he entered the New York City.
"He appears to have followed almost exactly to a 'T' the instructions that ISIS has put out in its social media channels before, with instructions to their followers on how to carry out such an attack," John Miller, New York Police Department commissioner for intelligence and counterterrorism, said at an earlier news conference.
A handwritten "document" found near the scene had both Arabic and English text, and included the message that the Islamic State would endure, the complaint said.
In the vicinity of a place where Saipov was shot, he dropped the weapons, which appear to be a paintball gun and pellet gun, and a black bag.