Stephen Cohen, a professor emeritus of Russian studies at New York University and Princeton University, says the Trump administration's decision to supply lethal weapons to Ukraine was a "mistake."

In an interview with radio host John Catsimatidis in New York, Cohen said that it was clear that President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE — like former President Obama — did not want to approve a plan to provide the new arms to Ukraine, but decided to do so in an attempt to shirk allegations that he has acted as a "Putin puppet."

"Look at what Trump is accused of every day, in all the newspapers, of being an agent of the Kremlin," Cohen said. "His nervous system is clearly cracking under these charges and he thinks this will get this monkey off his back."

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Cohen, who has in the past voiced skepticism of allegations of collusion between the Trump campaign and Russia, also criticized the breadth of ongoing investigations into Moscow's role in the 2016 presidential election.

He said that indictments stemming from special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE's investigation into Russian meddling in the election gave the appearance of Kremlin-linked wrongdoing, but in reality had nothing to do with Russia.

"What you're ending up with as Mueller gets guys to plead to financial crimes, is you're getting 'Russiagate' without Russia," he said. "So I don't know where this is leading."

Mueller's investigation has so far turned up charges against former Trump campaign chairman Paul Manafort Paul John ManafortFBI official who worked with Mueller raised doubts about Russia investigation Our Constitution is under attack by Attorney General William Barr Bannon trial date set in alleged border wall scam MORE and one of his associates for money laundering, tax evasion and failing to register as a foreign agent, among other charges.

George PapadopoulosGeorge Demetrios PapadopoulosTale of two FBI cases: Clinton got warned, Trump got investigated Trump says he would consider pardons for those implicated in Mueller investigation New FBI document confirms the Trump campaign was investigated without justification MORE, a former foreign policy adviser to Trump's campaign, and Michael Flynn, Trump's first national security adviser, have both pleaded guilty to lying to the FBI about their contacts with people linked to the Russian government.

Trump and his allies have denied allegations that the campaign conspired with the Russian government to disrupt and influence the 2016 presidential election, and the president himself has called Mueller's investigation a "witch hunt."