As the logic of the rumor goes, five American soldiers were killed for five Iranians taken; Karbala was an IRGC message to release its colleagues — or else.
Good thing I am not in charge....I would hang the five and tell the IRGC that is the fate of anyone else caught with their fingers in the pie. To remind them of the seriousness....I would also take out five Iranian oil platforms as a subtle reminder of what is like to play in the big leagues. They would either decide to stifle or get stuck in....both of which can be dealt with.
Thus far, the IRGC have not been slapped...and negotiation will not work with them. They see us as weak and vulnerable because we have not stood against them as we should have.
I agree with everything you say....they are a force to be reckoned with and not be under-estimated.