The man who admitted to orchestrating a plot to bomb the city's subways took the stand Tuesday in the trial of his high school classmate.
Najibullah Zazi testified for the prosecution against Adis Medunjanin and will resume his testimony in Brooklyn federal court on Wednesday.
Zazi and Zarein Ahmedzay, who testified Monday, have already admitted to their roles in the 2009 plot to detonate suicide bombs on Manhattan subway trains.
According to Zazi, the two confessed terrorists and Medunjanin made an oath in Queens to fight U.S. soldiers in Afghanistan, in retaliation for the mistreatment of Muslims.
"We made an oath, we would go join Taliban," Zazi testified.
Both Zazi and Ahmedzay testified that the three Flushing High School classmates traveled to Pakistan in 2008 and were trained by al-Qaeda on using machine guns and rocket launchers.
Zazi's testimony could persuade the jury, as he was the one making the explosive vests for the attempted subway attack.
Medunjanin's attorney, Robert Gottlieb, denied his client ever agreed to kill Americans for al-Qaeda and said he could not wait to cross-examine Zazi.
"The issues in this case are going to be known by the end of the trial. You have to wait until cross-examination to put this witness and every witness in order," said Gottlieb. "So ultimately, it will be up to the jury as to the significance of Zazi or anybody else."
Defense attorneys will try to get Zazi to admit the training in Pakistan had nothing do with bombing subways.
Medunjanin faces life in prison if convicted of conspiracy and terror charges.