Canada should have been warned in advance by the Americans of U.S. President Donald Trump's plan to kill a high-ranking Iranian military general with a drone strike, say two senior government sources.

Ottawa also wants a more thorough explanation from the Trump administration of the thinking behind the attack, according to federal government sources with direct knowledge of the situation.

CBC News spoke with the sources on the condition of anonymity, as the individuals are not authorized to speak publicly.

It's not clear exactly what the Trudeau government saw as unsatisfactory in Washington's stated rationale for killing a senior military official in a foreign country.

One source said that it's hard to work as part of a military coalition, like the one pursuing the remnants of ISIS in Iraq, without solid co-operation among members — and with the most powerful partner in that coalition pursuing a path its allies don't fully grasp.

Searching for an explanation

Asked today by host Chris Hall of CBC Radio's The House whether Canada had received any advance notice of the plan to kill Soleimani, Foreign Affairs Minister François-Philippe Champagne said he could not "go into the specifics of operations or intelligence."

Champagne said that, "following the death of Gen. Soleimani, we had — and I think that's what Canadians would expect from us — put our force (in Iraq) under what we call force protection ... So despite the missiles that were fired by Iran, all the Canadians and coalition troops and Iraqis were safe."

Trump administration officials have claimed Soleimani was actively planning attacks against Americans. President Trump himself claimed the infamous Iranian military leader was scheming to "blow up" an American embassy, but offered no evidence to back that up.

Members of the U.S. Congress on both sides of the aisle have complained bitterly about the lack of information about the attack coming from the administration.

Canada has about 500 troops in Iraq; some have been moved to Kuwait in recent weeks in response to the ongoing volatility on the ground. About half of those Canadians are with the NATO training mission, while the others — including up to 250 special forces members — are involved in the U.S.-led anti-ISIS coalition.

The recent tensions in the region flared up on Dec. 27, when an Iranian-backed militia group killed an American contractor in Iraq.

Those tensions escalated to the brink of open warfare one week ago, when the U.S. retaliated by launching a drone strike that killed Iran's top military general, Qassem Soleimani. He is said to be responsible for at least 600 American deaths.

Dire consequences

In response to Soleimani's killing, Iran launched 16 ballistic missiles early Wednesday at two military bases in Iraq housing U.S. military personnel. Some Canadian military personnel were also present at one of the bases at the time of the attack.

In the immediate aftermath of Soleimani's death, Canada recognized the significance of the Americans' action and security officials immediately began gathering information to brief Prime Minister Trudeau, the first source said. The PM was on vacation in Costa Rica at the time.

The first source said officials at the highest levels of the Canadian government feared that the act of killing Soleimani threatened to trigger dire consequences in the region.

That source stressed, however, that the event won't fundamentally change the Canada-U.S. relationship. Canada remains fully committed to the principles of the NATO mission in Iraq and continues to share the overall security objectives of the U.S., the source said.

Rescue workers search the scene where a Ukrainian plane crashed in Shahedshahr, southwest of the capital Tehran, Iran, on Wednesday, Jan. 8, 2020. (Ebrahim Noroozi/THE ASSOCIATED PRESS)

The stakes for Canada in the standoff in the Middle East ramped up Thursday when Trudeau announced that Canada has evidence indicating that Ukraine International Airlines Flight PS752 was shot down by Iran, possibly by accident.

The passenger jet crashed outside Tehran early Wednesday morning local time, hours after the Iranian missile attack, killing all 176 people on board — 57 of whom, the government now says, were Canadians.

'I think it is too soon to be drawing conclusions," Trudeau says. 0:31

The first source said that, at this stage in the investigation, Canada is not focusing on who's to blame for the crash. Trudeau was asked multiple times during Thursday's press conference whether he thinks the U.S. is partially responsible for the crash, given the sequence of events.

"I think it is too soon to be drawing conclusions or assigning blame or responsibility in whatever proportions," Trudeau told reporters gathered at Ottawa's National Press Theatre.

"Right now, our focus is on supporting the families that are grieving right across the country and providing what answers we can in a preliminary way, but recognizing that there is going to need to be a full and credible investigation into what exactly happened before we draw any conclusions."

Due to the time difference with Iran, top government officials in Ottawa first learned of the crash late Tuesday night as they were wrapping up a top secret briefing on the Iran crisis.

The first source said some officials had gathered together in an office, while others joined the confidential meeting by a secure telephone line. As the meeting was coming to a close, David Morrison, the foreign and defence policy adviser to the prime minister, was told a plane had just gone down in Tehran.

Canadian authorities were ordered to gather information throughout the night. The source said it was clear from the start that there would have been Canadians on that flight.

The source added that Canada did not have credible information about the probable cause of the crash until late Wednesday, after Canadian officials had spent much of the preceding 24 hours gathering information.

Top officials, including Chief of the Defence Staff Gen. Jonathan Vance and senior bureaucrats, gathered to discuss all of the available intelligence Thursday morning, the source said.

They came to the conclusion that the most probable cause of the crash was an Iranian missile strike, then briefed Trudeau and some members of his cabinet. Shortly afterward, Trudeau held his second press briefing in two days.

CBC News reached out to the Prime Minister's Office but received no comment on the record by publication time.