But Mr Trump tweeted that the judicial process at the Cuban detention centre takes longer than the federal court system.
Trump said in a tweet, in reference to the FBI's statement that Saipov, a resident of New Jersey, was inspired by the ISIS and "requested to display ISIS's flag" in his hospital room.
And now the president is calling for the death penalty for the suspect in the bike path attack in NY. He also said there is "something appropriate" about keeping him in NY. In another tweet, Trump said prosecutors "Should move fast". He killed 8 people, severely injured 12. But so far, Trump has treated terror suspects just as President Barack Obama did, passing on Guantanamo in favor of having his own Justice Department lawyers try them in federal court.
Prosecutors said Saipov had 90 videos and 3800 photos on one of his two mobile phones, many of them Islamic State-related pieces of propaganda, including images of prisoners being beheaded, shot or run over by a tank.
"The defence is sure to raise this as unfair and raising questions about a jury being able to reach an impartial verdict", said James Acker, a criminal justice professor at the State University of NY in Albany who specialises in capital punishment.
"I will consider the president's comments as mitigation evidence as I arrive at an appropriate sentence", the judge, Colonel Jeffery R. Nance of the Army, reportedly said during the hearing last month at Fort Bragg.
Investigators work around the wreckage of a Home Depot pickup truck a day after it was used in a terror attack in NY on November 1, 2017. Prosecutors say he recruited and facilitated the travel of foreign fighters to join the Islamic State and extradited him from Bosnia.
Turkish PM thanks Georgian PM for contribution to Baku-Tbilisi-Kars Railway
President Erdogan and Azerbaijan's President Ilham Aliyev reviewed the guard of honor and saluted the Azerbaijani soldiers. The rail link between Azerbaijan and Georgia was modernized under the project, which was launched in 2007.
By Thursday morning, Trump himself said Saipov would be prosecuted in NY, which the president said would be faster than subjecting him to a military tribunal at Guantanamo.
This handout photograph obtained via the Federal Bureau of Investigation shows Mukhammadzoir Kadirov, 32, in a poster obtained November 1, 2017 saying it was "seeking information.in relation to the deadly attack in the Tribeca neighborhood of New York City" on October 31, 2017.
Trump opened the morning with a burst of tweets about his policy priorities and a blast at Schumer, the Senate Democratic leader.
No one held within the USA has been sent to Guantanamo since the detention center opened in January 2002 to hold suspected members of al-Qaida and the Taliban.
Tuesday's assault was the deadliest in NY since the September 11, 2001, when more than 2600 people died in the World Trade Centre attack.
The president had said Wednesday he would consider sending Saipov to Guantanamo Bay.
Trump has passed on other chances to send suspects there, including earlier this week, when the Justice Department said a militant captured in Libya and accused of playing an instrumental role in the 2012 Benghazi attacks would be prosecuted in federal court in Washington, where a trial for the alleged mastermind is already under way.