The USS Vincennes - and Iran Air flight 655 - very sad loss.
The USN was in the Persian Gulf protecting Kuwaiti tankers from attacks. At the time of the missile strike on the Iran Air flight, the Vincennes was in a battle with several Iranian gunboats.
The USS Stark attack which killed 37 sailors was fresh in the commanders memories. The area was considered a war zone due to the deadly attacks on tankers and other traffic in the Gulf region.
Unfortunately for the Iran Air flights crew and passengers, the IFF aboard the Airbus A300 failed to respond to the ship's routine interrogations. The failure was documented by numerous radio and radar recordings on and off the Vincennes. The IFF system is designed to discern freindlies from possible threat aircraft.
In addition to the equipment failure aboard the doomed airliner, the Iran Air crew was apparently not monitoring the civilian emergency frequency when several calls went out with course and speed data. Guard frequency was also used in an attempt to ward off the fast approaching aircraft.
The airliner,off course about 4 miles west of the normal route by commercial air traffic was headed directly for the Vincennes. There were no AWACS aircraft aloft to assist with ID.
President Reagan stood behind the captains decision and while he was publicly 'saddened' by the loss, I don't believe there was ever a formal apology although I feel that there should have been despite the wartime posture of both countries.
Certainly not a happy story, but completely different situation than the Soviet attack that brought down a Korean Air flight.