Justin Trudeau emerged on Wednesday afternoon to deal publicly with the world as it is, in all its complexity and danger.

Not for the first time, a Canadian prime minister was asked about an American military adventure. Not for the first time, the response required a combination of diplomacy and differentiation.

The unanswerable question is what else might happen next.

The alarming prospect of armed conflict between the United States and Iran was superceded in Trudeau's remarks by the deaths of 63 Canadian citizens in the crash of a Ukraine International Airlines flight near Tehran. Only after dealing with that tragedy did the prime minister turn to what he described as the "deeply concerning events in Iraq."

Trudeau specifically and explicitly condemned the Iranian military's firing of missiles into American military bases in Iraq, including one base where Canadian soldiers were stationed.

"We continue to encourage a de-escalation of tensions and a dialogue in the region," the prime minister said.

Prime Minister Justin Trudeau saysthe decision to launch the drone attack on Iranian Major-Gen. Soleimani was made by the U.S. based on their own threat assessment. 0:34

Only in response to a reporter's question did he comment on Donald Trump's decision to order the targeted killing of Iranian military commander Qassem Soleimani — the act that prompted Iran to launch two dozen missiles into Iraq on Tuesday night.

"Canada has long been aware of the threat posed by the IRGC on regional and global safety and security," Trudeau said after being asked whether he accepted the American claim that Soleimani posed an imminent threat. "The Americans made a decision based on their threat assessment."

This was neither a condemnation nor an endorsement of the American action — and it has the effect of maintaining some distance between this country and what the American president has done.

Pearson and Johnson, Trudeau and Nixon

From Vietnam to Iraq, there are precedents for keeping our distance, however uneasily.

Lester B. Pearson famously provoked Lyndon Johnson's ire in March 1965 when the prime minister went to Philadelphia and delivered a speech in which he called for a temporary halt to American bombing in North Vietnam. Johnson grabbing Pearson by the lapels and lecturing him at Camp David is one of the more iconic moments in the history of Canadian-American relations.

Eight years later, Pierre Trudeau ran afoul of Richard Nixon over another wave of U.S. bombs.

That Trudeau, like this one, had just been narrowly re-elected with a minority that depended on the NDP for survival. With the stridently anti-war New Democrats pushing for a resolution that would condemn the American bombing of Hanoi, the Liberal government introduced a motion that both deplored the bombing and called on all sides to cease "acts of a warlike nature."

President Richard Nixon in the White House with Prime Minister Pierre Elliott Trudeau on March 24, 1969. (The Associated Press)

Nixon was furious and Canada-U.S. relations dropped into a deep chill for the remainder of Nixon's time in office. According to historical accounts, Nixon pointedly declined to send a letter of condolence when Trudeau's mother died sometime after the resolution was passed.

Trump the unpredictable

Nixon was perhaps not the most calm or rational man to ever occupy the White House, but even his approach to power seems relatively cautious when you compare him with Trump. Justin Trudeau is, like all of his predecessors, compelled to mind the economic and political realities of this country's relationship with the United States. But no prime minister has ever been faced with a president less reliable or predictable than the current occupant of 1600 Pennsylvania Avenue.

When surveyed last year, 71 per cent of Canadians said they didn't trust Trump to do the "right thing" in world affairs. Point of comparison: 59 per cent of Canadians said they believed George W. Bush would do the right thing in 2003, the year he led the United States into the war in Iraq.

That sense of insecurity hangs over this situation like a dark cloud, even on a day when it seemed like cooler heads had somehow prevailed.

Further retaliation by the Iranians is not inconceivable and it remains unclear what the Americans imagine they'll do next. Trump said publicly on Thursday morning that he would be asking NATO to become more involved in the Middle East — though Trudeau told reporters that the president has made no specific request.

Dealing with all of that will test Trudeau at a time when he's trying to rehabilitate his government and his own credibility. And he will be pressed on all sides by rival parties who want him to be somehow tougher, or clearer, or more involved. If the House of Commons had been sitting this week, the NDP no doubt would have pushed Trudeau to condemn the killing of Soleimani, just as his father's government publicly criticized the bombing of Hanoi.

For at least as long as Donald Trump is president, there are going to be more moments like this. It's also not guaranteed that things will go back to normal whenever the next president is sworn in.

Figuring out how Canada should navigate this new world has become the necessary objective of Trudeau's presence on the world stage. It's a challenge he may end up passing on to his successors.