In its defense, the Vincennes believed they were about to be attacked by an Iranian F-14 armed with anti-ship missiles (Iran's F-14s were not so-equipped). The previous year, 37 sailors were killed and 21 wounded when an Iraqi Mirage mistakenly (Saddam was our ally at the time) fired a pair of Exocets at the USS Stark.
As for "para-military" and all that, Iran Air 655 was squawking its normal code, was maintaining standard contact with ATC in English, and was flying its standard 28-minute route from Tehran to Dubai. But despite well trained operators in front of a control panel way superior to that of the Buk, they still managed to screw up.
 Aegis control room on the USS Vincennes |