"As unfortunate as it sounds, it's increasingly apparent to me that the Cold War has never left Vladimir Putin's mind; I think he still thinks in those terms," Harper said on the eve of his meeting with German Chancellor Angela Merkel.
"We simply, as a world, cannot afford the risk of Europe going back to being a continent where people seize territory, where they make claims on neighbouring countries, where the bigger military powers are prepared to invade their neighbours or carve off pieces."
Germans know this better than anyone, Harper suggested.
"This is a world we cannot go back to — I know the feeling about that in Germany particularly. We cannot go back to this. It represents an enormous long-term threat to peace and security."
The prime minister's comments were similar to those made a short time later by U.S. President Barack Obama, also in Europe after attending the Nuclear Security Summit held in The Hague earlier this week.
Obama, Harper and the five other G7 leaders — those of Britain, Germany, Japan, France and Italy — held an emergency meeting on the sidelines of the nuclear summit. They emerged to effectively boot Russia out of the G8 as retaliation for its annexation of Ukraine's Crimea peninsula shortly after the pro-Western uprising in Kyiv last month.
"Once again we are confronted with the belief among some that bigger nations can bully smaller ones to get their way," Obama said in Brussels.
"So I come here today to insist that we must never take for granted the progress that has been won here in Europe and advanced around the world. Because the contest of ideas continues, for your generation, and that’s what is at stake in Ukraine today."
A senior European diplomat suggested Wednesday that Harper's comments about Putin, made during a question-and-answer session with business leaders in Munich, are accurate.
The Russian president has never accepted the disintegration of the former Soviet bloc and views the uprising as "the second time Russia lost Ukraine," said the official, speaking on condition of anonymity because he wasn't authorized to brief the media.
European leaders are convinced Putin has his sights set on a greater chunk of Ukrainian territory, but hasn't acted yet because he's testing the waters of international reaction, the diplomat said. The goal is to turn Ukraine into a "failed state," he added.
Harper and Merkel will discuss the crisis in detail Thursday in Berlin. The two leaders are the most senior in the G7 and have a close relationship.
Some European nations, including Germany, have been hesitant to level strong economic sanctions against Russia given their close ties to Moscow and the fragility of their economies following the 2008 global economic meltdown.
But in recent weeks, Merkel has been open to much tougher sanctions. She was reportedly infuriated by the false assurances Putin gave her about having no designs on Crimea.
The prime minister met German business leaders in Munich to extol Canada's economic virtues and discuss the Canadian-European Union trade deal, but even in a corporate setting, the ominous events of eastern Europe were a key topic of discussion.
Nonetheless, Harper's events in Germany were focused on promoting Canada to the European powerhouse. The two countries did nearly $19 billion in trade last year.
The prime minister was asked about Canada's energy sector at one point during the event. He expressed skepticism that Germany would be able to meet its goal of phasing out fossil fuels and nuclear energy while having a scant supply of hydro power.
"I do not know an economy in the world that does not rely heavily on at least one of those, so this is a brave new world you're attempting; we wish you well with that," he said to seemingly nervous laughter from the crowd.
Harper added it would be "very challenging" for Germany not to rely on some combination of fossil fuels, nuclear and hydro, but said Canada was ready to help.
"What I tell audiences at home and abroad is: Whatever the energy mix of the future is, Canada will be a major producer," Harper said, adding the country's current challenge is its overwhelming dependence on the Canadian and American markets.
"We're looking for ways to take that business, obviously, global."
The senior EU diplomat said European nations are, in fact, determined to find alternatives to Russian natural gas amid the biggest crisis in eastern Europe since the Cold War.
They're also aggressively lobbying NATO to boost "infrastructure" spending — in other words, build military bases — in new EU nations like Romania, Poland and Slovakia.
Despite skepticism about the weight of the economic sanctions already taken against Russia, the targeting of the Bank Rossiya, in particular, is "very good and will be painful for Russia's elite," another European diplomat said.
Eastern Europeans are advising Canada and the U.S. to expand the sanctions to include Russian lawmakers who voted for the use of force in Ukraine, he added.
— With files from Murray Brewster in Ottawa
Follow Lee-Anne Goodman on Twitter at @leeanne25
Also on HuffPost