WASHINGTON — An Iranian missile accidentally brought down a Ukrainian jetliner over Iran this week, killing everyone aboard, American and allied officials said on Thursday, adding a tragic coda to the escalated military conflict between Washington and Tehran.
Prime Minister Justin Trudeau of Canada said his country had intelligence that an Iranian surface-to-air missile brought down the jetliner, which was carrying 63 Canadians among its some 176 passengers and crew. Mr. Trudeau said his conclusion was based on a preliminary review of the evidence but called for a full investigation “to be convinced beyond all doubt.”
“We recognize that this may have been done accidentally,” Mr. Trudeau said at a news conference in Ottawa. “The evidence suggests very clearly a possible and probable cause for the crash.”
United States officials had a “high level of confidence” that the Iranians brought down the airliner by mistake, one American official said. The official said that two missiles fired from an Iranian air defense system, the SA-15, shot down the airliner.
The Ukrainian airliner, a Boeing 737-800, went down on Wednesday morning. It had turned back toward the Tehran airport before it crashed in a huge explosion minutes after takeoff, according to an initial Iranian report released on Thursday. The report said that the plane, bound for Kyiv, the Ukrainian capital, was in flames before it hit the ground but did not send a distress signal.
Although both the United States and Iran now appear to be backing away from a larger military confrontation, the new intelligence suggests that the loss of life from the downing of the plane was a direct result of those heightened tensions between the countries.
American satellites, designed to track missile launches, detected the firing of the Iranian short-range interceptor. United States intelligence agencies later intercepted Iranian communications confirming that the SA-15 system brought down the Ukrainian airliner, officials said.
A security camera captured the impact — first the predawn darkness, then a series of blinding bursts of light in the distance, followed by a storm of burning debris in the foreground.
The circumstances of the disaster raised suspicions that the airliner was brought down by a missile. The crash occurred just hours after Iran launched a barrage of ballistic missiles at United States targets in Iraq, with Tehran presumably bracing for possible American retaliation.
American officials have been reluctant to publicly assign blame for the downing of the aircraft, apparently to keep from inflaming tensions with Iran, at a time both governments were taking steps to de-escalate the military confrontation that came to a head when an American drone killed Maj. Gen. Qassim Suleimani, one of the most senior figures in Iran’s government.
The SA-15 missile is designed to operate at medium to very low altitude and intercept both aircraft and guided weapons, according to military documents. It has a maximum range of 15.5 miles and can intercept aircraft and missiles at an altitude of up to 32,800 feet.
A mobile system, the SA-15 could have been brought out by the Iranian military to defend the airport if officials believed the United States military was intending to counter attack after the missile strike. If the Iranians thought that the United States was going to target their airport or other facilities with guided missiles, the SA-15 system could have been used to try to intercept them.
The SA-15 can track multiple targets, and seek to shoot down two at once, meaning it can fire multiple missiles nearly simultaneously, according to the military documents.
The comments from American officials came after the Iranians invited the National Transportation Safety Board of the United States to assist in the investigation despite previous reports that the Americans would not be involved, according to correspondence reviewed by The New York Times.
The board has reached out to the State Department to determine how to proceed, according to two people familiar with the matter who spoke on condition of anonymity because the correspondence was not public. Sanctions against Iran prevent Boeing from contacting the Iranians without an export license, the people said.
On Wednesday, a spokesman for Iran’s armed forces, Abolfazl Shekarchi, was quoted by the Iranian news media as saying that the crash was not a result of any military action.
“This is ridiculous,” Mr. Shekarchi was quoted as saying. “Most of the passengers on this flight were our valued young Iranian men and women. Whatever we do, we do it for the protection and defense of our country and our people.”
The SA-15 launch was detected by the American military’s Space-Based Infrared System, which relies on satellites in various orbits to track the launch and flight path of ballistic missiles. While American missile defense sensors are primarily meant to defend against long-range launches, the military has upgraded the infrared satellite network to track shorter-range ballistic missile launches as well. They also can often detect launches of air defense systems, including missile systems designed to work at low altitudes, officials have said.
The infrared system also detected the antiaircraft missile fired by Russian-supported separatist fighters in eastern Ukraine in 2014 that brought down Malaysia Airlines Flight 17, officials said at the time. All 298 people aboard were killed.
The satellite data is often combined with other sources of information. For example, American intelligence can also often detect when air defense radar are turned on or activated, giving clues to what systems have been used.
On Wednesday, American officials combined the information from the satellites with intelligence from intercepted calls.
President Trump, speaking at the White House on Thursday after an event announcing new environmental regulations, was asked about the downed airliner.
“I have my suspicions,” he said. “I don’t want to say that because other people have their suspicions also. It’s a tragic thing when I see that. It’s a tragic thing.”
He added that the crash could have been an accident.
“But somebody could have made a mistake on the other side,” Mr. 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, personally. So we’ll see what happens.”
On Thursday, Oleksiy Danilov, secretary of the National Security and Defense Council of Ukraine, said that investigators were following up on unconfirmed reports that fragments of a Russian-made Tor surface-to-air missile — a system used by Iran — had been found near where the plane, a Boeing 737-800, came down.
Ukraine was negotiating with Iran to allow the investigators to search the crash site near Tehran for possible rocket fragments, he told Censor.net, a Ukrainian news outlet.
The possibilities of a terrorist act, a collision with an airborne object such as a drone, and an engine explosion were also being examined as possible causes of the crash, Mr. Danilov said on his Facebook page.
Ukraine brings unique experience to bear on the case because of the 2014 Malaysia Airlines flight. The SA-15 is similar to the same type of missile system that caused that crash, meaning the passengers aboard the flight out of Tehran may have faced a similar fate: silence followed by a sudden explosion that sent shrapnel and debris spiraling through the fuselage before the aircraft’s uncontrolled descent toward the ground.
Julian E. Barnes and Eric Schmitt reported from Washington, Anton Troianovski from Kyiv, Ukraine, and Natalie Kitroeff from New York. Reporting was contributed by Thomas Gibbons-Neff from Washington, Andrew E. Kramer from Moscow, Maria Varenikova from Kyiv and Dan Bilefsky from Montreal.