By Nate Raymond

NEW YORK (Reuters) - A dual citizen of Iran and the United States was found guilty on Tuesday on charges that he tried to help acquire surface-to-air missiles and aircraft components for the government of Iran in violation of U.S. sanctions.

Reza Olangian, 56, was convicted by a federal jury in Manhattan on all four counts he faced, including conspiring to acquire and transfer anti-aircraft missiles, prosecutors said.

Olangian faces a mandatory minimum prison sentence of 25 years and a maximum of life. He is scheduled to be sentenced on March 13.

Lee Ginsberg, Olangian's lawyer, said the verdict "was very disappointing and we do plan to appeal."

Olangian, who became a U.S. citizen in 1999, was arrested in Estonia in October 2012 and subsequently extradited to the United States following a sting operation orchestrated by the U.S. Drug Enforcement Administration.

Prosecutors said that in 2012, Olangian met in Ukraine with a DEA informant posing as a Russian weapons broker to arrange for the purchase of surface-to-air missiles and various military aircraft components.

In recorded conversations and emails, Olangian described his plans to acquire the missiles and parts and smuggle them into Iran, for whose government he was purchasing them, from Afghanistan or from another neighboring country, prosecutors said.

Prosecutors said Olangian negotiated a deal involving 10 missiles and dozens of aircraft parts, and during a video conference with the informant, stated that he ultimately wanted to acquire at least 200 missiles.

The deal followed a failed effort by Olangian in 2007 to obtain about 100 missiles for Iran, prosecutors said. His goal throughout, they said, was to make a substantial profit selling the weapons.

At trial, Ginsberg described Olangian as having been active in protests against the Iranian government during his U.S. college studies and said he had moved back to Iran when it appeared the country might become more democratic.

But after the election of Mahmoud Ahmadinejad as president in 2005, Olangian began engaging with people involved with selling weapons to get Iran to agree to buy them and expose the government "for what they were all about," Ginsberg said.

"It was his desire to get the Iranian government on the hook on a contract, on a piece of paper, that would definitely show what they were trying to do," Ginsberg said in his opening statement.

(Reporting by Nate Raymond in New York; Editing by Leslie Adler)