The US National Transportation Safety Board (NTSB) will join the probe into the crash of the Ukrainian passenger plane.
In a statement posted on its Twitter account, the agency said it had received formal notification of the crash from Iran.
The US-made Boeing 737, operated by Ukraine International Airlines went down shortly after takeoff from Tehran airport in the early hours of Wednesday.
Canada, which had dozens of passengers on board, has also appointed an expert, while a team from Ukraine has already held discussions in Tehran.
Canadian Prime Minister Justin Trudeau said earlier the jet might have been brought down by an accidental Iranian missile strike, citing intelligence sources.
Israel says it is poised to move on Rafah
China evacuates entire town as record rains, winds lash its south
More than 100 pilot whales stranded in Western Australia, experts say
Grand jury indicts 18 in Arizona fake elector scheme
India inspects spice makers over alleged contamination
