The homegrown terrorists accused of plotting to shoot down military planes and blow up synagogues were idiots who knew nothing about explosives and were duped into the plot by an FBI informant, their lawyers said yesterday.

Attorneys for the four men, busted last year on terrorism charges that included plans to bomb two Riverdale synagogues and shoot down military aircraft at Stewart Air National Guard Base in Newburgh, made their case for bail at a hearing in federal court in White Plains.

Judge Colleen McMahon said she would make a ruling later in the week. Earlier, she had warned the defendants that there would be "no guarantees."

Defense lawyers argued that an FBI informant entrapped James Cromitie, 44, David Williams, 28, Onta Williams, 32, and Laguerre Payen, 27, bribing them with money and, in one case, a BMW.

"These four clients did not plan anything," said Susanne Brody, a lawyer for Onta Williams. "The government planned every step of the way."

Brody said they only practiced with missile launchers for a half-hour.

"You need a little more than the 30 minutes of training to operate this equipment."

The only one whose lawyer didn't argue for bail was Payen, from Haiti, who doesn't qualify because of his citizenship.

Prosecutor David Raskin argued that entrapment was a weak defense considering the defendants were prepared to blow up buildings.

Raskin told the judge that prosecutors expected to obtain hundreds of documents of evidence within about three weeks.

Last week, the judge slammed prosecutors for withholding the evidence and ordered them to scour Homeland Security international-terrorism files to obtain it.

reuven.fenton@nypost.com