How do you talk to a terrorist holding hostages?

(CNN) - Australian officials had tried to negotiate the release of the hostages with the gunman before storming the cafe, but the ISIS sympathizer and self-proclaimed Islamic cleric Man Haron Monis remained defiant, leading Australian special forces and police to eventually storm the Lindt Chocolate Cafe after a 16-hour standoff.

At least two of the 17 hostages were killed during the rescue attempt, while four others were wounded.

A former Navy SEAL and member of the hostage working group in Iraq says, unfortunately, this might have been the inevitable outcome.

"[Man Haron Monis] may have already had in his mind that, 'I'm going to do the martyr's death.' You know, you call it in the states, suicide by cop. That may have been his intention all along. The negotiator probably may have come to that conclusion: to advise the on-scene commander that this guy is going out one way and one way only," said Daniel O'Shea. "And when those hostages had the chance to escape, it prompted something that launched the mission to go in and go rescue the surviving."

The decision to initiate a rescue mission in any hostage situation is a "last resort," O'Shea stressed, particularly considering the risk to other lives such mission entails.

"To send in hostage rescue forces - it's the most difficult mission that you can operate. It has to be surgical, it has to be precise and the challenge of it, as you saw, as these hostages were running out and the guys were trying to make an entry point, you know, really the safest things hostages can do in that environment is to get down."

For more of our interview with former Navy SEAL Daniel O'Shea, watch the interview above.