Officials believe Iran mistakenly fired at Ukrainian plane Iran has formally invited the NTSB to send a representative to the Ukraine plane crash site. The NTSB says it will not speculate on the cause of the crash. Kris Van Cleave reports that the Iranian military was on high alert following its air strikes on U.S. forces in Iraq and U.S. officials believe shooting down the passenger jet may have been a mistake made in the heat of the moment.