Iranian-American citizen Manssor Arbabsiar was sentenced Thursday to the maximum 25 years prison by a US judge who said his role in a bizarre plot against the Saudi ambassador to Washington could not be "tolerated."
Arbabsiar, 58, pleaded guilty last October to conspiring with Iranian military elements to hire assassins from the Mexican drug mafia to kill the Saudi envoy.
New York federal Judge John Keenan told the court that Arbabsiar "fully realized his act. He must learn the lesson."
"That cannot be tolerated," Keenan said of the plot.
Defense lawyers argued that Arbabsiar was not fully responsible because he suffered from bipolar disorder, but Keenan said he'd been found competent and he dismissed lawyers' request for a sentence of just 10 years.
Arbabsiar, wearing a blue prison outfit, read from a prepared statement in a quiet voice, saying: "What I did wrong, I take responsibility. I can't change it. I never hurt anyone. My mind is sometimes not in a good place."
"I know you have to punish me for the things I did wrong," he added.
Top New York federal prosecutor Preet Bharara welcomed the result.
"Manssor Arbabsiar was an enemy among us -- the key conduit for, and facilitator of, a nefarious international plot concocted by members of the Iranian military to assassinate the Saudi ambassador to the United States and as many innocent bystanders as necessary to get the job done," he said in a statement.
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The plot, if carried out, would have caused "unspeakable harm," Bharara said.
The acting assistant attorney general for national security, John Carlin, also applauded the heavy sentence, saying Arbabsiar was being "held accountable for his role in this assassination plot."
"I applaud all those responsible for ensuring that Arbabsiar and his co-conspirators in Iran's Qods Force failed in their efforts. Today's sentencing serves as a reminder of the evolving threat environment we face," he said.
Arbabsiar was arrested in September 2011 at New York's John F. Kennedy International Airport, leading to a major legal and diplomatic drama between Washington and Tehran, amid already tense relations.
He was charged along with co-defendant Gholam Shakuri, a senior member of the Iranian Revolutionary Guard's elite Quds Force, who is at large.
Iran strongly denied any involvement in what the United States said was a plot originating with the Quds Force, Iran's covert external action unit, to kill the ambassador by hiring assassins from a Mexican drug cartel for $1.5 million.
To set up the alleged hit, Arbabsiar allegedly arranged for $100,000 to be wired to the United States as a down payment, the indictment said.
Arbabsiar's lawyer, Sabrina Shroff, urged leniency, telling the court that he had never been in trouble before, "was a good father and a very good son."
However, prosecutor Glenn Kopp said Arbabsiar could not escape justice.
"He worked for over six months to assassinate a foreign ambassador on American soil," he said.