Canadian Prime Minister Justin Trudeau said Thursday "multiple" intelligence sources indicate that Iran shot down a Ukrainian airliner after it took off from Tehran, killing all 176 on board, including 63 Canadians.
Trudeau's comments came as images posted on social media increasingly pointed to a catastrophic mistake by Tehran's air defense batteries bringing the down Ukraine International Airlines Flight PS752 in flames Wednesday.
Citing information from allies as well as Canada's own intelligence, the prime minister said the plane appeared to have been hit by an Iranian surface-to-air (SAM) missile.
"We know this may have been unintentional. Canadians have questions, and they deserve answers," Trudeau told reporters.
The prime minister was backed by other Western leaders, including British Prime Minister Boris Johnson who said mounting evidence supported a missile strike, which "may well have been unintentional."
US President Donald Trump indicated that Washington officials believed the Kiev-bound Boeing 737 was struck by one or more Iranian missiles before it ditched and exploded outside Tehran.
Flight PS752 went down just minutes after takeoff from Tehran airport in the dark early Wednesday, with no radio message from the pilot to indicate distress, according to the Iranian Civil Aviation Organization.
It was carrying 82 Iranians, 63 Canadians, 11 Ukrainians, 10 Swedes, four Afghans, three Germans and three Britons.
The disaster unfolded amid worries of a possible war between the United States and Iran, just hours after Tehran launched ballistic missiles at American military targets in Iraq in retaliation for the January 3 US drone strike in Baghdad that killed a top Iranian general.
The Iranian government said the missile strike scenario made "no sense," however, arguing that several internal and international flights had been sharing approximately the same airspace.
Tehran later asked Ottawa to share its information with Iranian investigators.
- 'Canadians want answers' -
Trudeau said Canada was working with allies to ensure a credible probe takes place.
"The families of the victims want answers, Canadians want answers, I want answers," he said.
"That means closure, transparency, accountability, and justice. This government will not rest until we get that."
Johnson called Thursday for a full, transparent investigation.
"It is vital that there should be an immediate and respectful repatriation of those who've lost their lives to allow their families to grieve properly," the British leader said.
"The UK continues to call on all sides urgently to deescalate to reduce tensions in the region."
- 'I have my suspicions' -
Trump would not directly confirm what US intelligence was saying privately.
"I have my suspicions," Trump said. "It was flying in a pretty rough neighborhood and somebody could have made a mistake."
"Some people say it was mechanical. I personally don't think that's even a question," he said, adding that "something very terrible happened."
But unnamed officials told US media satellite, radar and electronic data indicated Tehran's air defense units downed the aircraft.
ABC News reported that an unnamed official said it was "highly likely" the plane was brought down by two SAMs.
Ukraine called for United Nations support for a broad investigation, and sent 45 crash investigators to Tehran to take part in the inquiry led by Iranian authorities.
Investigators are pursuing several possibilities, including engine failure, a missile strike or an act of terror.
"If any country has information that can help conduct a transparent and objective investigation into the tragedy, we are ready to receive it and cooperate in further verification," the Ukraine presidency said in an English-language statement.
Ali Abedzadeh, head of Iran's civil aviation organization and deputy transport minister, said Iran and Ukraine were "downloading information" from the aircraft's black boxes retrieved from the crash site.
"But if more specialized work is required to extract and analyze the data, we can do it in France or another country," he said.
Analysts were examining photographs posted online of the wreckage and a private video apparently taken of the flight when it was struck for evidence that it was downed by a missile.
The New York Times said it had verified the video showing a small explosion apparently when a missile struck the aircraft.
"I think this has a very good possibility of being accurate," John Goglia, a former US aviation safety expert on the National Transportation Safety Board, said of the missile theory.
"Airplanes that have just taken off and have made a climb to 8,000 feet, that's entering the safest period of time in the flight. So even an engine failure at that altitude should not cause the type of event we've just observed," he told AFP.
The Ukrainian airline crash brought back memories of another tragedy involving a US military error.
In 1988, an Iran Air flight was shot down over the Gulf by a surface-to-air missile fired from the US warship USS Vincennes.
All 290 people aboard, most of them Iranians, were killed, sparking outrage across the country.
The US Navy had mistaken the aircraft for an Iranian fighter jet.