The NY Times is also reporting the missile story. Included in their report, however, is this interesting tidbit:
. . . the Iranians, through the International Civil Aviation Organization, 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 two people familiar with the matter who spoke on condition of anonymity.
https://www.nytimes.com/2020/01/09/w...h-ukraine.html