Russian President Vladimir Putin likely considered a phone call from President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE earlier this year as a sign of "weakness" or "incoherence," according to a former U.S. ambassador to Russia.

"I think Putin can only interpret this as signs of weakness or, at a minimum, incoherence in the president’s approach to the relationship," Alexander Vershbow said Monday on CNN.

Trump berated Putin during a March 20 phone call over a Russian propaganda video that appeared to show a nuclear missile falling on Florida, Axios reported on Sunday. Trump's Mar-a-Lago resort is located in Palm Beach, Fla.

During the same phone call, Trump congratulated Putin on his recent reelection, ignoring notes from aides that warned "DO NOT CONGRATULATE," according to the The Washington Post.

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Vershbow was U.S. ambassador to Russia from 2001-2005 after serving as U.S. ambassador to NATO from 1998-2001.

"The president seems ready to sweep all of the difficult issues under the carpet, even the Russian military buildup that was displayed in that video with all these new ‘wonder weapons’ that Putin’s very excited about," Vershbow said.

Trump also warned Putin during the March phone call that the U.S. would win an arms race against Russia, Axios reported.

"There may be some basis for limiting the arms race," Vershbow said. "We could certainly use to de-escalate the military side of the relationship, but solving problems like Ukraine, a more balanced approach to Syria, those are where I don’t see the Russians meeting us even halfway."

Putin and Trump are holding a historic summit in Helsinki on Monday. Trump said they will discuss issues such as trade, arms control and China.

The U.S. president previously said he would bring up Russia's support of Syrian leader Bashar Assad and Russia's military actions in Ukraine, but his ultimate goals remain unclear.

Trump on Sunday said he has "low expectations."