Western leaders by consensus agreed Thursday that Iran shot down a Ukrainian passenger jet, killing all 176 passengers on board, but they conspicuously stopped short of expressing the kind of outrage and vitriol that has previously defined criticism of Tehran's aggression.

The amenable approach – involving the frequent use of words like "mistake" and "unintentional" – appeared to reflect the gravity of recent tensions between Iran and the U.S. and a recognition of how close they came to war earlier this week.

Perhaps most surprising among the responses was President Donald Trump's. He spoke shortly after a U.S. official confirmed to multiple media outlets that a Russian-made Iranian surface-to-air missile brought down the Boeing airliner near Tehran roughly four hours after Iran launched a missile strike against two U.S. bases in Iraq. That attack served as retaliation for Trump's decision to kill Iranian Gen. Qassem Soleimani by drone strike – the latest in a series of events that earlier this week appeared to represent a march to war. The governments of Canada and Britain publicly agreed with the official's assessment.

"Well, I have my suspicions," Trump said calmly in an event at the White House marking a rollback of environmental regulations. "Other people have those suspicions also."

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"But somebody could have made a mistake on the other side," Trump said, adding that the aircraft "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."

For its part, Iran fired back at the U.S. claims almost immediately. Iranian Brig. Gen. Abolfazl Shekarchi, a spokesman for the Iranian armed forces, called the U.S. official's claims "ridiculous" and "psychological warfare" by the Americans.

"Most of the passengers on this plane were invaluable Iranian youth; everything we do is aimed at defending our people's and country's security," Shekarchi said, according to state news service Fars .

But the president's more muted comments were a sharp contrast with aggressive statements he made as recently as last week, amid the fallout from a December rocket attack by pro-Iranian militia against a U.S. base near Kirkuk, Iraq, that resulted in the death of an American contractor. He warned Iran would pay "a big price" and that the U.S. will "hit back" if it engages in any provocative actions.

Thursday's statements follow a general easing of tensions that Western leaders seem to have put forward this week, apparently recognizing that unnecessary aggression regarding a neighborhood as tumultuous as Iran's could still easily devolve into all-out conflict.

Canadian Prime Minister Justin Trudeau, among the most outspoken about the incident in its aftermath, also struck a measured tone despite the fact that 60 Canadians were on board the aircraft and died in the crash.

"We have intelligence from multiple sources including our allies and our own intelligence that evidence indicates that the plane was shot down by an Iranian surface-to-air missile," Trudeau said in a public appearance. "This may well have been unintentional. This new information reinforces the need for a thorough investigation into this matter."

British Prime Minister Boris Johnson acknowledged in a statement "a body of information that the flight was shot down by an Iranian surface to air missile." But he, too, treaded lightly in assigning blame.

"This may well have been unintentional," Johnson said. "We are working closely with Canada and our international partners and there now needs to be a full, transparent investigation."

Investigators from Ukraine arrived at the crash site by Thursday afternoon, officials tell U.S. News. The government of Ukraine has so far withheld attributing any particular blame for its passenger jet's crashing, though its leaders were equally intent on avoiding placing blame prematurely, particularly following early reports of the U.S. official's assessment about the Iranian missile.

"At this moment an official group of Ukrainian experts and searchers is working at the place of the tragedy," the Ukrainian Embassy in Washington, D.C., wrote to U.S. News in an email. "We are monitoring all media statements and working closely with our foreign partners, including those countries who suffered from this tragic crash."

Among the more contentious elements of the aftermath of the crash were reports Iranian investigators had gathered the black boxes from the site of the crash but had so far refused to grant access to any outsiders. The Ukrainian official who spoke with U.S. News did not know whether the Ukrainian investigation team had seen them.