Federal prosecutors said that additional, unspecified charges in the form of a superceding indictment will be filed against Zazi at some point in the future. They offered no particular date.
It came as a surprise to the defense.
"He's already facing life in prison on this charge," Zazi's attorney, J. Michael Dowling, said. "I don't know what their gameplan is."
The case was adjourned until a status conference on Fedruary 16 at 11 a.m. The judge said trial is now likely to take place next fall.
"I think that's probably too quick," Dowling said after the proceedings.
Prosecutors did not address TV and other reporters outside the courthouse.
When asked about his client, Dowling said: "He is doing well, considering. He is not depressed. He is in fairly good spirits under the situation."
Zazi said nothing throughout the 17 minute proceeding, sitting rigid on the edge of his chair. He did not move, even slightly.
Federal authorities say Zazi received explosives training from al-Qaida on a trip to Pakistan.
Zazi is charged with conspiring to use weapons of mass destruction. He denies any wrongdoing.
Authorities say Zazi planned a large-scale terrorist attack, possibly on New York City's transit system.
Court papers allege he bought and tested bomb-making materials in a Denver suburb before traveling to New York.