A onetime decorated U.S. Army sniper instructor known as Rambo was sentenced Tuesday to 20 years in prison for conspiring in a plot to kill a Drug Enforcement Administration agent.

Joseph Hunter, 51, was sentenced in Manhattan by U.S. District Judge Laura Taylor Swain, who said he made the "dishonorable choice" to join a conspiracy to kill the agent and a cooperating witness in Liberia in 2013 and to recruit others for assassination assignments.

Hunter was to be paid $100,000 while two snipers he recruited were to be paid $700,000, prosecutors said. The others — a former U.S. Army soldier and an ex-German soldier — already were each sentenced to 20 years in prison.

She called his crimes "grave and serious" and said post-traumatic stress syndrome could not earn him leniency.

"His was a choice that betrayed society and the honor and trust that this country invested in his military career," Swain said.

Still, she showed leniency, sentencing him below the minimum of 25 years sought by prosecutors but above the 10 years requested by the defense.

Hunter was honorably discharged from the U.S. Army in July 2004 as a sergeant first class after 20 years.

But prosecutors said in court papers that since 2009, he had participated in numerous murders, shootings and torture for an international drug group and then bragged to others that "it's easy to kill."

When he spoke in court Tuesday, Hunter cried and blamed his crimes on forgetting "to place God at the forefront of my thoughts and actions."

He said he was ashamed and embarrassed but "forever grateful" for those who remained supportive, including a sister, who dabbed her eyes with tissues as she watched the proceeding.

"I have shamed them, a good family, good friend," he said.

Lawyers in the case said his Army service included training soldiers in marksmanship and tactics, five years of classified missions and five years as a drill instructor at Fort Knox, Kentucky. Afterward, he did private security for firms during two tours of Iraq.

Defense lawyers said he had received numerous awards, including a certificate presented by President George W. Bush, the Global War on Terrorism Medal and the Kentucky Colonel, awarded by his home state.

After leaving the Army, Hunter passed the entrance exam to join the New York Police Department but did not pursue it because he thought it would be too expensive to raise a family of four in New York, according to court papers. So the family settled in Owensboro, Kentucky, and he worked over a year as a classification treatment officer in Kentucky. The judge said he strayed into sniper work for the money.

Hunter was brought to the United States in 2013 to face conspiracy charges.

Hunter pleaded guilty to conspiracy charges after his arrest in the sting operation.