The elder statesman among all former Canadian ambassadors to the United States says he's never seen the relationship between the two governments quite this cool.

When it comes to Canada-U.S. relations, Allan Gotlieb has a unique vantage point.

It's not just that his tenure in Washington goes farther back than any other living U.S. ambassador. It's that his own time in D.C. straddled two distinct eras — the depth of the Trudeau-Reagan relationship to the height of the Mulroney-Reagan-Bush bond that culminated in a free-trade pact.

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What he sees now is a relationship that's neither at its best, or worst, just most distant.

"I think the relationship is as cool as I ever remember," said the 86-year-old ex-diplomat, who wrote a pair of books about his Washington posting between 1981-89.

"I can't speak for the Diefenbaker era, I wasn't at the foreign ministry then. But it's as cool as I remember."

He was speaking in an interview this week, a day after President Barack Obama vetoed legislation to build the Keystone XL pipeline.

In past disagreements, Gotlieb said there was hostility against the neighbour's policies. As an example, he said Trudeau's National Energy Program infuriated the U.S. administration. In his time there were also disputes about cross-border TV ads, softwood lumber and, until there was a deal, acid rain.

But in those days, he said, American presidents paid special attention to Canada-U.S. issues. Ronald Reagan even campaigned on the idea of a North American Accord in 1980.

Obama, meanwhile, hasn't made a bilateral visit to Canada since his first month in office. Gotlieb lays much of the blame on the president, not the prime minister.

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"The Keystone project has been handled with considerable insensitivity. Our history has been characterized by ... a sensitivity to each other's interests," he said.

"And I think some of that is intrinsic in the style of Obama. He sees his legacy, maybe, as standing up to big oil and Canada's interests are secondary to the much bigger primary interest of Obama to go down in history as the man that stopped carbon from heating up our planet."

Don't get him wrong — he's not declaring doom and gloom.

Canada and the U.S. remain each other's top trading partner, with $2 billion in goods and services swapped each day; there's military co-operation in the Middle East; federal departments deal directly with one another on scores of different initiatives; the governments are working on harmonizing industrial regulations across a range of sectors; and the historic reopening of U.S. relations with Cuba began in Canada, a fact Obama acknowledged and expressed gratitude for.

He gives Canada's prime minister credit for keeping his cool throughout the Keystone affair.

"The relationship I'd say is correct," Gotlieb said. "In a context where strong language could well have been used, in Canada, because of White House insensitivity to our relationship and our joint interests, I think (Prime Minister Stephen) Harper has been restrained. I don't think there's anything he could have done differently."

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He doesn't believe that more aggressive action on climate-change in Canada would have made a difference on the Keystone file, which he says has been dictated by political considerations in the U.S.: "I don't buy that for a minute."

As for what comes next, he says, who knows.

"I don't know. There could be another Ronald Reagan — and maybe even if there's not another Ronald Reagan we might look back on this period to say Obama was anomalous," he said.

"I don't think the way to see the Canada-U.S. relationship today is to say it's bad. It's just not the same. It may never be the same... It's different now."

Meantime, the current U.S. ambassador to Canada, Bruce Heyman, put a different spin on the relationship Thursday in remarks to the Ottawa Chamber of Commerce.

"We're still partners, and like every partnership, there are challenges, and yes, there are opportunities," Heyman said.

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"We have the longest unprotected border in the world; that's an opportunity. We have the largest trading relationship in the world; that's an opportunity. We share values and language and history; that's an opportunity."