"The planned attacks included detonating bombs in Times Square and the New York City subway system and shooting civilians at specific concert venues", the US DoJ said in a statement.
The charges against Canadian citizen Abdulrahman El Bahnasawy, 19, Philippine citizen Russell Salic, 37, and Talha Haroon, a 19-year-old United States citizen residing in Pakistan, were revealed in court.
El Bahnasawy has already pleaded guilty to terrorism offenses, federal prosecutors said, but his conviction was sealed while the probe continued. El Bahnasawy will be sentenced in December and could face life in prison; the other two men could also spend the rest of their lives behind bars, if convicted.
The defendants conspired to carry out the attacks during the Islamic holy month of Ramadan in 2016, which ended on July 5 a year ago, according to court documents. The three men meant to attack in the Summer of 2016 in support for ISIS.
Salic boasted of his "public figure" status to the undercover agent, sending the following message: "I$3 ts not strict here".
But Haroon and his accomplices were arrested before any attack could be carried out. He is awaiting extradition to the United States.More news: Unseasonably warm, humid weekend in Lancaster; remnants of Hurricane Nate arriving Monday
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According to the District Attorney, multiple locations around New York City were targeted, including Times Square and the subway system as well as an array of concert venues.
On May 5, 2016 Mr Haroon said the subway was the "perfect target" and they should try and attack as many people as possible, including women and children.
The complaints lay out in chilling detail the lengths the men went to plan attacks in crowded areas with maximum casualties, and allege they spoke numerous times of killing as many people as possible.
They said Salic, who had a pro-Islamic State social media presence, told the undercover agent he was prepared to transfer money to help fund the attacks and claimed to have previously sent money to other countries to support the Islamic State. El Bahnasawy allegedly wrote told the undercover officer that he was hoping to "create the next 9/11", and Salic allegedly told the undercover officer "i$3 t would be a great pleasure if we can slaughter" people from NY. Around May 6, he told the agent he had researched concerts in the New York City area looking for one in a "closed area" and "far away from cops". Five workers who survived the incident filed the charges against Salic.
The report also stated that according to prosecutors, he had communicated with an undercover Federal Bureau of Investigation agent and said he wanted to "shoot up concerts cuz they kill lots of people".
Haroon, who has been accused of five counts of the indictment, was arrested in Pakistan in September 2016. Prosecutors said that Al Bahnasawy likewise spoke with a covert operator acting like an ISIS sympathizer about needing to "shoot up shows cuz they murder bunches of individuals".