Defreitas, a 66-year-old naturalized U.S. citizen from Guyana, and Kadir, 58, were arrested in 2007 after an informant infiltrated the plot and recorded them discussing it.
Prosecutors alleged that Defreitas and Kadir wanted to kill thousands of people and cripple the American economy by using explosives to blow up the fuel tanks and the underground pipelines that run through an adjacent Queens neighborhood. Authorities say the men sought the help of militant Muslims, including an al-Qaida operative, in Guyana.
The defendants wanted to set off an explosion "so massive ... that it could be seen from far, far away," Assistant U.S. Attorney Zainab Ahmad said in closing arguments. Their vision prompted them to code name the plot "The Shining Light," the prosecutor said.
The two men shut their eyes when the verdict was read and whispered quietly to their attorneys. During the trial, their lawyers described the two men as clueless trash-talkers who were led astray by the informant, a convicted drug dealer.
Kadir maintained his innocence. "Obviously, he's totally disappointed," said his attorney, Kafahni Nkrumah.
"There's more than just the evidence Mr. Kadir was coming up against," Nkrumah said. "There's the atmosphere of fear in the country ... of Muslims, Islam and fear of terrorists, especially in New York City."
Defreitas' attorney Mildred Whalen said there wouldn't have been a case without the government's intervention.
"I think it was clear these guys couldn't act on their own ... and didn't act on their own," Whalen said. "We're deeply disappointed."
Both defendants planned to appeal.
Prosecutors relied heavily on the informant's secret recordings, which captured Defreitas bragging about his knowledge of Kennedy Airport and its vulnerabilities.
"For years, I've been watching them," he said of the fuel tanks while on a reconnaissance mission with the informant.
He also marveled at the lack of security, saying, "No solider. Nothing at all."
In other tapes, Defreitas ranted about punishing the United States with an attack that would "dwarf 9/11." He told the informant his U.S. citizenship gave him cover.
"They don't expect nobody in this country to do something like this," he said. "They have their eyes on foreigners, not me."
Kadir testified in his own defense, denying he was a militant Muslim who spied for Iran for years before joining the JFK scheme. He told jurors that he warned the plotters: "Islam does not support aggression or killing innocent people."
As part of the plot, Defreitas and the informant traveled to Guyana to try to meet with Kadir and show him homemade videotapes of the airport's so-called fuel farms. The plotters also discussed reaching out to Adnam Shukrijumah, an al-Qaida member and explosives expert who was believed to be hiding out in the Caribbean at the time.
Shukrijumah, an FBI-most wanted terrorist, was indicted in federal court in Brooklyn this month on charges he was involved in a failed plot to attack the New York City subway system with suicide bombers.
Another man, Abdel Nur, pleaded guilty to a lesser charge in the case and is awaiting sentencing. A fourth suspect, Kareem Ibrahim, had his case severed from the others' after he fell ill. It's not clear when he would be tried.