Khalid Ali-M Aldawsari, who is from Saudi Arabia, entered his plea at his arraignment at the federal courthouse in Lubbock, Texas. The U.S. magistrate on the case set a May 2 trial date.
If convicted of attempted use of a weapon of mass destruction, he faces up to life in prison and a $250,000 fine.
U.S. District Judge Sam Cummings, the trial judge, issued an order early March prohibiting Aldawsari's attorney or prosecutors from speaking about the case.
According to court documents, Aldawsari allegedly hatched plans to attack various U.S. targets, including places in New York City and former President George W. Bush's Dallas home.
The 20-year-old, who was legally in the U.S. on a student visa, was arrested Feb. 23. Court documents indicate authorities traced Aldawsari's online purchases, discovered extremist online posts he made and secretly searched his apartment, computer and email accounts, and read his diary.
The terrorism case detailed in court documents was significant because it suggests that radicalized foreigners can live quietly in the U.S. without raising suspicions from neighbors, classmates, teachers or others. It also showed how quickly U.S. law enforcement can move when tipped that a terrorist plot may be unfolding.
Authorities said a North Carolina chemical company reported $435 in suspicious orders by Aldawsari to the FBI on Feb. 1. In a separate instance, a Michigan-based shipping company notified Lubbock police and the FBI the same day with similar suspicions because it appeared the order was not intended for commercial use.
Prosecutors allege that Aldawsari bought 30 liters of concentrated nitric acid from a Georgia company and three gallons of concentrated sulfuric acid that are combined to make TNP.
The FBI later found the chemicals in Aldawsari's apartment as well as beakers, flasks, wiring, a Hazmat suit and clocks.
Aldawsari entered the U.S. in October 2008 from Riyadh, Saudi Arabia, to study chemical engineering at Texas Tech University. He transferred in 2011 to nearby South Plains College, where he was studying business. A Saudi industrial company, which was not identified in court documents, was paying his tuition and living expenses in the U.S.
Aldawsari wrote that he was planning an attack in the United States for years, even before coming to the U.S. on a scholarship.
He said he was influenced by Osama bin Laden's speeches and that he bemoaned the plight of Muslims.