Russian President Vladimir Putin has become a reoccurring theme in election year 2016, between Donald Trump’s public praise of Putin to allegations of a Russian hack into the Democratic Party’s computer system.

“I haven’t seen an election like this in my lifetime,” said former Ambassador to NATO Nicholas Burns, while visiting the Jackson School at University of Washington this week.

Burns, a career diplomat, served as an advisor for both Presidents George H.W. Bush and Bill Clinton on Russian affairs. He says Trump’s comments this campaign season, perceived as expressing sympathy for Putin’s agenda, break all traditional boundaries.

Background on Trump's past comments on Russia and Ukraine

“Republicans and Democrats….if you look at John McCain, Mitt Romney, Marco Rubio, Barack Obama, Hillary Clinton—They all agree that Russia is a problem, that Russian aggression is a problem. That Russian aggression in Georgia and Ukraine has been a major serious crisis in the United States that we have to use our power, not to fight the Russians but to defend our allies in Western Europe, and Trump does not agree with that,” Burns told KING 5. “He’s made a lot of excuses for Putin, and at first I thought, this is just a verbal mistake, he just got it wrong; he’ll apologize for it. He’s been saying this for a year.”

On Tuesday, Trump's running mate Mike Pence revealed an apparent split from the top of the ticket on the subject of Russia, calling Putin “small and bullying.”

“Pence was taking positions that were 180 degrees different than Donald Trump,” Burns said of the debate.

Previously, Pence had defended Trump’s comments, calling Putin a stronger leader than President Obama.

On Wednesday, Trump gave more ambiguous comments about his relationship with Putin, while talking to reporters the day after the VP showdown.

"I don't love, I don't hate, we'll see how it works, we'll see,” Trump said.

Former Ambassador Burns, who supports Hillary Clinton, says regardless of who is elected, Russia will remain a key challenge for the next president.

“We’re in a place where in Europe, we're containing Russian power, and that's the right strategy, but on some of these bigger global issues, Russia is a force in the world, so we need to deal with them. It doesn't mean we like Putin, it means you have to be sophisticated enough to deal with them,” he explained.

Burns says other major global issues on the next president's desk include continued instability in the Middle East and a complicated relationship with China.

“I think the next president is going to face one of the most complex and daunting set of global challenges in our memory.”