At a moment of awful revelation Thursday, the prime minister emphasized the need for clarity.

"The families of the victims and all Canadians want answers. I want answers," Justin Trudeau said during his second press conference in as many days. "That means closure, transparency, accountability and justice. And this government will not rest until we get that."

Looking grim, Trudeau began with words for the families of those who died aboard Ukraine International Airlines Flight PS752 and then officially stated what was already being whispered — that there are good reasons to believe the plane was shot down by an Iranian surface-to-air missile, perhaps unintentionally.

His immediate and repeated demand was for a "thorough" investigation. He did not flash outrage or deliver condemnation. Pronouncing anyone's guilt right now might only undercut the pursuit of a full explanation for what happened in the skies over Tehran this week.

Prime Minister Justin Trudeau says Iran shot down the airliner containing 63 Canadians but a full investigation is required to determine if it was deliberate. 0:59

There will be plenty of time for anger in the days ahead. Trudeau's responsibility right now is to do everything he and his government can to get to accountability.

Maybe no Canadian prime minister has faced a tragedy quite like this one before now. But the long modern history of international conflict now sadly includes several examples of similar disasters.

Already, Trudeau has reached out to Mark Rutte, prime minister of the Netherlands, whose country lost 193 citizens when Malaysia Airlines Flight 17 was shot down by a Russian missile in 2014.

"He talked a lot about how it is, first of all, important to keep the families who are grieving apprised of information, even at preliminary stages," Trudeau said. "He also talked about the need for direct and real relationships with all different elements involved in the crash. He talked about the fact that he had multiple conversations with Russian authorities, including Vladimir Putin, in the days following the Malaysian Airlines downing."

Memories of Flight 655

In 1983, the Soviet Union shot down Korean Air Lines Flight 007, with 62 Americans aboard, and U.S. President Ronald Reagan was denunciatory in his response. Five years later, the Americans shot down Iran Air Flight 655 — killing all 290 people on board — and the response from the United States was evasive and flippant.

Not until 1996 did the United States, with the matter before the International Court of Justice, agree to pay $131 million in compensation to Iran and the families of the victims.

That tragedy is largely forgotten in the United States, but it's well-remembered in Iran. In fact, Iran's Supreme Leader invoked it this past Monday in a tweeted response to Donald Trump's recent belligerence.

One might imagine that experience would help the Iranian regime understand now Canadians' need for answers and accountability. But it's hard to know what kind of cooperation Canada can count on, particularly in a climate of open conflict between Iran and the United States.

Co-operation or consequences

Even a liberal democratic ally might be reluctant to open itself to international scrutiny and blame. Iran is a hostile nation and we have not had formal diplomatic relations with it for years.

Regardless, there will be pressure on Trudeau to ensure Iran co-operates — or to ensure consequences if it does not. That presumably will require working with allies and marshalling international support; a Canadian leader can't bang his fist on the table and count on other countries bowing before our economic and military might.

Prime Minister Justin Trudeau says he wants Iran to grant Canada access to the full investigation into the causes of the downed Ukrainian airliner 0:42

That, in addition to the need for further details, might explain why the prime minister stopped short of assigning blame or making threats on Thursday. But Trudeau's initial approach also might fit with what is now something of a doctrine for his government — that it neither escalates nor backs down.

That motto has been invoked in the context of both the NAFTA renegotiation and the ongoing diplomatic dispute with China. The tragedy of Flight PS752 may yet require something more of Trudeau than simply standing firm on a demand for answers — but not backing down now might at least offer a basis for a future response.

Trudeau will be called on to grieve and to console on behalf of the nation. He will, in the days ahead, bear a responsibility to those families and friends who want to recover the remains of their loved ones and get the answers — and the justice — that they deserve. But there will be occasion too for drawing firmer conclusions.

A day after the downing of Malaysia Airlines Flight 17, U.S. President Barack Obama addressed reporters in Washington. The United States was not so directly linked to that disaster — one American citizen was killed — but duty required the president to address the matter.

"Now is, I think, a sombre and appropriate time for all of us to step back and take a hard look at what has happened," Obama said. "Violence and conflict inevitably lead to unforeseen consequences."

It might have been easier for Obama to say that then. For Trudeau, saying something similar on Thursday might have been considered provocative — as if he were joining those who are linking the downing of PS752 to the American decision to kill the Iranian military leader Qassem Soleimani.



But, more broadly, Obama's words on unforeseen consequences seem applicable to all of these tragedies.

As an American analyst wrote on Thursday, tidy attempts to assign blame can be put aside, the lesson here is that "war is never cost free."