Evidence suggests an Iranian missile brought down a Ukrainian passenger plane that crashed near Tehran, possibly in error, Western leaders say.
The leaders of Canada and the UK called for a full and thorough investigation into the crash, which killed all 176 people on board.
Iran has ruled out a missile strike by its air defences.
The crash came just hours after Iran carried out missile strikes on two airbases housing US forces in Iraq.
US media have speculated that the timing of the crash suggests the plane may have been mistaken for a US warplane as Iran prepared for possible US retaliation for the strikes.
CBS News quoted US intelligence sources as saying a satellite detected infrared “blips” of two missile launches, followed by another blip of an explosion.
Meanwhile, Newsweek quoted a Pentagon and senior US intelligence officials, as well as an Iraqi intelligence official, as saying they believed Ukraine International Airlines flight PS752 was hit by a Russian-made Tor missile.