Three men who plotted to blow up New York City synagogues, a Jewish community centre and shoot down military planes have been released. 

The trio, who were convicted more than a decade ago of the plots, were ordered to be released from prison by a judge on Thursday who said they had been manipulated by the FBI.

The men have been named as Onta Williams, David Williams and Laguerra Payen, who were three of what became known as the "Newburgh Four."

A fourth individual, James Cromitie, did not seek compassionate release and is expected to serve until 2030. He was described as the ringleader by the US government.

In a scathing opinion against the FBI, US District Judge Colleen McMahon branded the men "hapless" petty criminals. 

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The group plotted to blow up synagogues in New York (Photo: HBO/Handout)

Judge McMahon said in a 28-page legal order that they were "easily manipulated" by the government in a sting operation.

She said all four men were caught up in a scheme in 2009 to attack the synagogues, community centre and launch stinger missiles at military aircraft, driven by overzealous FBI agents and an "unsavoury" confidential informant.

The judge granted compassionate release to three men and reduced their sentence to time served plus 90 days. She cited concerns for the men's health and her own qualms about the original 25-year-sentence she imposed on the men in 2011.

Addressing Cromitie, Judge McMahon wrote that Cromitie was a small-time "grifter" who was broke and unemployed when he was enlisted in the FBI driven plot, who provided fake bombs to plant in exchange for $250,000 in the "jihadist mission."

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Riverdale Jewish Center was one of the targets (Photo: Getty)

Cromitie enlisted the other three men to serve as lookouts, the judge said.

She added: “Nothing about the crimes was the defendants' own doing. The FBI invented the conspiracy.”

During the initial trial, Prosecutors said the defendants had spent months scouting targets and securing what they thought were explosives and a surface-to-air missile, aiming to shoot down planes at the Air National Guard base in Newburgh, New York, and blow up synagogues in Riverdale, a heavily Jewish part of the Bronx. 

They were arrested there after allegedly planting bombs that were, in fact, packed with inert explosives supplied by the FBI.

Speaking to AP, Samuel Braverman, who represented Payen at trial, called the ruling "incredibly brave and just."

He said: “What we need to take from all of this is: We have been entrapped by a pathology of criminalization and anger and blaming, and we need to do better as a society.

Amith R. Gupta, part of a group of lawyers representing Payen, Onta Williams and David Williams, added: “We are tremendously pleased that our clients are on their way home - even if it's fourteen years too late.

"Onta, David, and Laguerre were destitute when they were targeted and entrapped for their race, religion, and working class backgrounds by a government looking to spread fear of Muslims and justify bloated budgets. 

“We are grateful that the Court's long standing criticism of the government's conduct finally materialised into good news."

The Williamses are not related.